A Comprehensive Guide to orchid Culture Table ... - Venamy Orchids
A Comprehensive Guide to orchid Culture Table ... - Venamy Orchids
A Comprehensive Guide to orchid Culture Table ... - Venamy Orchids
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<strong>Venamy</strong> <strong>Orchids</strong><br />
1460 Route 22<br />
Brewster, New York10509<br />
A <strong>Comprehensive</strong> <strong>Guide</strong> <strong>to</strong> <strong>orchid</strong> <strong>Culture</strong><br />
Copyright 2002 <strong>Venamy</strong> <strong>Orchids</strong><br />
<strong>Table</strong> of contents<br />
1 Introduction <strong>to</strong> <strong>orchid</strong>s<br />
1.1 <strong>Orchids</strong> in the plant family<br />
1.2 What is an <strong>orchid</strong>?<br />
1.3 Structure of <strong>orchid</strong> flowers<br />
1.4 How <strong>orchid</strong>s grow in nature<br />
1.5 A bit of <strong>orchid</strong> his<strong>to</strong>ry<br />
1.6 Taxonomy / nomenclature<br />
1.7 Propagation of <strong>orchid</strong>s<br />
2 Potting <strong>Orchids</strong><br />
2.1 Growth pattern of <strong>orchid</strong>s<br />
2.2 Roots of <strong>orchid</strong>s<br />
2.3 Containers / supports for growing <strong>orchid</strong>s<br />
2.4 Potting materials<br />
2.5 Our potting mixes<br />
2.6 Potting <strong>orchid</strong>s-general<br />
2.7 Potting monopodial <strong>orchid</strong>s<br />
2.7.1 Potting Phalaenopsis & other monopodial <strong>orchid</strong>s in sphagnum moss<br />
2.7.2 Potting Phalaenopsis & other monopodial <strong>orchid</strong>s in bark<br />
2.8 Potting sympodial <strong>orchid</strong>s<br />
2.8.1 Potting sympodial <strong>orchid</strong>s in sphagnum moss<br />
2.8.2 Potting sympodial <strong>orchid</strong>s in bark<br />
2.9 Care after repotting<br />
3 Light levels for growing <strong>orchid</strong>s<br />
3.1 How is light measured / expressed<br />
3.2 Misconceptions about light.<br />
3.3 How light diffuses<br />
3.4 How <strong>to</strong> measure light<br />
3.5 What is low light, moderate light and bright light for <strong>orchid</strong>s ?<br />
3.6 Where <strong>to</strong> grow you <strong>orchid</strong>s at home<br />
3.7 Impact of light on your <strong>orchid</strong>s<br />
3.8 Light versus direct sunlight<br />
3.9 Growing under lights<br />
3.9.1 Spectrum (colors) of light and it’s impact on plants<br />
3.9.2 Horticultural Vs household lamps<br />
3.9.3 Output of light bulbs<br />
3.9.3.1 Fluorescent lights<br />
3.9.3.2 High intensity lamps<br />
3.9.4 Getting more information about light fixtures<br />
Toll Free: 1-800-362-3612<br />
Fax: (845) 279-2682<br />
venamy@<strong>orchid</strong>susa.com
4 Temperatures for growing <strong>orchid</strong>s<br />
5 Humidity levels for growing <strong>orchid</strong>s<br />
5.1 How much humidity ?<br />
5.2 Increasing humidity around your plants<br />
6 Fertilizing <strong>orchid</strong>s<br />
6.1 Introduction<br />
6.2 Contents of fertilizers<br />
6.3 Organic vs. inorganic fertilizers<br />
6.4 Which fertilizer(s) should we use ?<br />
6.5 Should we use the same amount of fertilizer year round ?<br />
6.6 Hormones, vitamins and other additives <strong>to</strong> the water<br />
6.7 Determining how much fertilizer <strong>to</strong> use in a gallon of water.<br />
7 Watering <strong>orchid</strong>s<br />
7.1 Quality of water<br />
7.2 How often <strong>to</strong> water<br />
7.3 When and how <strong>to</strong> water your <strong>orchid</strong>s<br />
7.4 Influence of PH on nutrient availability.<br />
7.5 How <strong>to</strong> adjust the PH of your watering solution<br />
7.6 The final word about fertilizing<br />
8 Pests and diseases<br />
8.1 Prevention, the best defense<br />
8.2 Pests that may affect your <strong>orchid</strong>s<br />
8.3 Treating insects with an insecticide.<br />
8.4 Making sure the treatment is effective<br />
8.5 Diseases<br />
9 Cultural problems<br />
9.1 Cultural problems common <strong>to</strong> most <strong>orchid</strong>s<br />
9.1.1 Leaves<br />
9.1.2 Leaves or new growth<br />
9.1.3 Buds, flowers & flower spikes<br />
9.1.4 Roots<br />
9.2 Cultural problems-Phalaenopsis<br />
9.2.1 Leaves<br />
9.2.2 Flower spike, buds, flowers<br />
9.3 Cultural problems - Cattleyas<br />
9.3.1 New growth & leaves<br />
9.3.2 Flower sheath, buds & flowers<br />
9.4 Cultural problems - Cymbidiums<br />
9.4.1 New growth, leaves<br />
9.4.2 - Flower sheath, buds & flowers<br />
9.5 Oncidiums and intergenerics with Oncidiums<br />
9.5.1 New growth, leaves<br />
9.5.2 Flower stem, buds & flowers<br />
9.6 Cultural problems - Paphiopedilums<br />
9.6.1 New growth, leaves
1.1 <strong>Orchids</strong> in the plant family<br />
1.2 What is an <strong>orchid</strong> ?<br />
1.3 Structure of <strong>orchid</strong> flowers<br />
1.4 How <strong>orchid</strong>s grow in nature<br />
1.5 A bit of <strong>orchid</strong> his<strong>to</strong>ry<br />
1.6 Taxonomy / nomenclature<br />
1.7 Propagation of <strong>orchid</strong>s<br />
1 Introduction <strong>to</strong> <strong>orchid</strong>s<br />
1.1 <strong>Orchids</strong> in the plant family<br />
In the plant family flowering plants form a group called Angiosperms. In this group there are lineages:<br />
• Amborellaceae: includes just one shrub that, according <strong>to</strong> the National Geographic (July 2002) “may be the<br />
closest living relative <strong>to</strong> the first flowering plant”.<br />
• Nymphaeaceae which includes the water lilies.<br />
• Illiciaceae which includes the star anises.<br />
• Magnoliids, which of course includes Magnolias, avocado and black pepper,<br />
• Monocots which with 65,000 species (1/4 of all flowering plants), are recognizable because they have just one<br />
seed leaf (single cotyledon). This group includes all grasses (corn, rice, wheat,...), palm trees (which are giant<br />
herbs) and flowers such as lilies and <strong>orchid</strong>s. <strong>Orchids</strong> by themselves account for nearly 25,000 species.<br />
• And, finally, Eudicots (formerly dicots because of their two seed leaves), the largest group of angiosperms with<br />
170,000 species, many of which are woody plants.<br />
Most of this information is from the above mentioned National Geographic issue.<br />
1.2 What is an <strong>orchid</strong>?<br />
What distinguishes <strong>orchid</strong>s from other flowering plants is the combination of three elements:<br />
• their pollen (called “pollinarium”, plural = pollina) which is formed in<strong>to</strong> a mass (usually 2 masses),<br />
• stamens and pistils are joined <strong>to</strong>gether in a structure called a “column”,<br />
• their seeds are very small (there may be up <strong>to</strong> 3 million in a seed capsule), they do not contain endosperm and<br />
have no organized embryo.<br />
1.3 Structure of <strong>orchid</strong> flowers<br />
Orchid flowers consist of:<br />
• the pedicel (the stem of the flower which includes the ovary),<br />
• the sepals,<br />
• the petals,<br />
• the column.<br />
Sepals and petals are in threes.<br />
The three sepals consist of the dorsal sepal and two lateral sepals.<br />
The three petals consist of two petals and a modified one called the labellum, or more commonly, the lip.<br />
1.4 How <strong>orchid</strong>s grow in nature<br />
Besides these morphological differences most <strong>orchid</strong>s differ from other plants by the way they grow in nature.<br />
Most <strong>orchid</strong>s are epiphytes, that is they grow attached on other plants (usually trees). They are not parasites, that<br />
is they do not take anything away from the plant they grow on, they merely use the other plant (tree) for support.<br />
Some <strong>orchid</strong>s are lithophytes, that is they grow on rocks.
Some other some are semiterrestrial, that is they grow on the ground, on decomposing plant material (not quite<br />
soil).<br />
And finally, a small number of <strong>orchid</strong>s are true terrestrial, meaning they grow in soil like most plants.<br />
1.5 A bit of <strong>orchid</strong> his<strong>to</strong>ry<br />
Confucius, the Chinese philosopher, grew <strong>orchid</strong>s in the fifth century BC and wrote a poem about them.<br />
Theophrastus, a Greek philosopher and scientist, mentions <strong>orchid</strong>s in his “Essay on Plants” published around<br />
300 BC<br />
Dioscorides, a Greek botanist, physician and pharmacologist mentioned <strong>orchid</strong>s in his work “De Materia<br />
Medica” ( “Of Medical Maters”) published around 60 AD This work remained a reference manual till the<br />
Middle Age (1,400 - 1,500 AD).<br />
<strong>Orchids</strong>, in those times, were believed <strong>to</strong> have medicinal properties, one of them being an aphrodisiac.<br />
And about 2,000 years ago Greeks gave <strong>orchid</strong>s the name “orkhis” which means testicle, because of the form of<br />
their pseudobulbs (pseudo = Greek for “false”).<br />
In more recent times, the first record of <strong>orchid</strong>s in cultivation dates back <strong>to</strong> 1731 in England. Philip Miller mentioned<br />
several <strong>orchid</strong>s in his second edition of “Dictionary of Gardening” (1768).<br />
Records of the Kew Royal Botanical Gardens show that Epidendrum cochleatum flowered for the first time in<br />
cultivation in 1787. Ten years later 15 <strong>orchid</strong> species were cultivated at Kew.<br />
Cultivation of <strong>orchid</strong>s started in earnest in the 19th century. At that time <strong>orchid</strong>s were brought <strong>to</strong> Europe by<br />
companies or individuals who financed collecting expeditions. They commissioned professional collec<strong>to</strong>rs who<br />
traveled for months all over the world in search of showy new species. Like treasure hunters these expensive<br />
enterprises were often shrouded in secrecy and it was not unusual for them <strong>to</strong> spread misleading information<br />
about the locations where new <strong>orchid</strong>s were found.<br />
New exotic <strong>orchid</strong>s were most often sold at Protheros & Morris & Stevens Sales Rooms in London, fetching<br />
extravagant prices.<br />
At that time very little was known about the cultivation of <strong>orchid</strong>s and their survival rate was dismal.<br />
Through experimentation and by gathering more information on the growing conditions of <strong>orchid</strong>s in their natural<br />
habitat, knowledge was slowly being developed and by 1851 B. S. Williams published the first edition of<br />
“The Orchid Grower’s Manual”.<br />
By the end of the 19th century there was enough experience and knowledge about the growing conditions of<br />
<strong>orchid</strong>s that many <strong>orchid</strong>s survived and bloomed in England’s greenhouses.<br />
Today there is a wealth of knowledge about growing <strong>orchid</strong>s and modern propagation methods have driven<br />
prices <strong>to</strong> affordable levels. Affordable prices, the fascination exercised by their captivating beauty and their<br />
diversity has made them increasingly popular houseplants.<br />
1.6 Taxonomy / nomenclature<br />
The International Code of Botanical Nomenclature (I.C.B.N.) and the International Code of Nomenclature of<br />
Cultivated Plants (I.C.N.C.P.) govern the naming of <strong>orchid</strong>s.<br />
The I.C.B.N. has standardized classification of plants and imposed the following endings:<br />
family<br />
tribe<br />
subtribe<br />
: aceae.<br />
: eae.<br />
: inae.<br />
Example: Orchidaceae<br />
Example: Vandeae.<br />
Example: Sarcanthinae.<br />
Below the subtribe are the genera (singular = genus). Examples: Cattleya, Dendrobium, Phalaenopsis, ...<br />
Note: all of the above have their first letter capitalized.<br />
Within the genera are the names identifying individual plants. Example: Phalaenopsis amabilis or Phalaenopsis<br />
Ever Spring.<br />
Names of species are not capitalized: Phalaenopsis amabilis designates a species,
i.e. a naturally occurring plant. Names of hybrids (man made crosses) are always capitalized as in Phalaenopsis<br />
Ever Spring.<br />
Finally, within a group of individual plants they may be variations which, for example, may be noted<br />
Phalaenopsis amabilis var. formosana.<br />
Variety is often abbreviated as “var.” and is usually reserved for species. For hybrids, varieties will be identified<br />
by adding <strong>to</strong> the name one or several words placed in single quotes as in Phalaenopsis Ever Spring ‘Light’.<br />
All new plants (species and hybrids) are registered with the Royal Horticultural Society of London.<br />
The name of <strong>orchid</strong>s is decided by the discover for new species or by the first person who registers a new<br />
hybrid.<br />
Until a new hybrid is registered it will be identified by the name of it’s parents, separated by an X. For example:<br />
Phalaenopsis amabilis x Phalaenopsis violacea or Phalaenopsis (amabilis x violacea) or Phalaenopsis amabilis x<br />
violacea or, in abbreviated form, Phal. amabilis x violacea.<br />
1.7 Propagation of <strong>orchid</strong>s<br />
There are several ways <strong>to</strong> propagate <strong>orchid</strong>s.<br />
Propagation from seed or sexual propagation<br />
Pollen is used <strong>to</strong> pollinate a flower. When the seed pod matures (which may take several months), the tiny seeds<br />
can be sowed.<br />
Not all seed pods will contain seeds as one or the other parent may be sterile.<br />
The encapsulated seeds are in a sterile environment as long as the seed pod is closed. It will eventually crack<br />
open at a certain time, in which case the tiny seeds will have <strong>to</strong> be decontaminated before sowing them.<br />
Most people prefer <strong>to</strong> work with a “green pod”. That is a seed pod that has matured but is collected before it<br />
starts <strong>to</strong> open.<br />
The seed pot is externally disinfected <strong>to</strong> kill any germs, spores, contaminants, ... that may be on it’s surface then<br />
it is cut open with a disinfected <strong>to</strong>ol (scalpel,...).<br />
Then the seed masses are sown in<strong>to</strong> a flask which contains a nutrient solution (the flask and its contents were<br />
previously sterilized in an au<strong>to</strong>clave). This flask is called a “mother flask”.<br />
This whole operation has <strong>to</strong> be performed in a sterile environment. Commercial growers will use an apparatus<br />
called a laminar flow hood (see page 36 of An Introduction <strong>to</strong> <strong>Orchids</strong> South Florida Orchid Society<br />
The nutrients solutions contain minerals, sugars, charcoal, sometimes banana extracts or coconut milk, ... Agar<br />
(a substance like gelatin) is added <strong>to</strong> make the solution more or less solid.<br />
The flask is sealed, marked / labeled and placed in a growth chamber / room where light is relatively limited and<br />
temperatures are relatively constant.<br />
After several weeks <strong>to</strong> several months the tiny seeds will germinate. When they have they will have <strong>to</strong> be transferred<br />
<strong>to</strong> several other flasks in an operation called “replating”. This is necessary because the mother flask may<br />
contain from several hundred <strong>to</strong> several thousand seeds which now need room <strong>to</strong> grow.<br />
The replated flask may still contain a hundred <strong>to</strong> several hundred plantlets, which is way <strong>to</strong>o many plants for the<br />
limited space of the flask.<br />
Again after several months the plantlets will be replated and they may need a third replate (some growers replate<br />
4 times !) until they are in their final flask which may contain from 10 <strong>to</strong> 40 plantlets.<br />
As for the mother flasks, all the replate flasks contain growing media which is different from the germination media.<br />
The new replating flasks with their nutrients where sterilized in an au<strong>to</strong>clave and the flasks <strong>to</strong> be replated where<br />
externally decontaminated. The replating operations are done in the sterile environment of a laminar flow hood.<br />
Plants resulting from sexual propagation may look like the mother plant or like the father or a combination of<br />
both or they may have characteristics of ances<strong>to</strong>rs. In other words they may display very diverse traits.<br />
Among these siblings one or several may be significantly more appealing or different than the others. Whoever<br />
possess this plant may recognize its uniqueness by adding a variety name <strong>to</strong> its name. The variety name is<br />
placed in single quotes as in Phal. Ever Spring ‘Light’ or Phal. Ever Spring ‘Cardinal’ or whatever the owner<br />
fancies <strong>to</strong> name the variety. Only that plant and it’s tissue or stem propagated progeny are entitled <strong>to</strong> bear the<br />
variety name.
Tissue culture<br />
As its name suggest tissue culture is done by using plant tissue, mostly the minuscule center of a new growth. A<br />
lot of experiments have been made trying <strong>to</strong> do tissue culture out of leafs, roots,... but so far the most successful<br />
method uses tissue from a new growth.<br />
The tissue is excised (cut), its outer layers are removed till the active center of developing cells, the meristem, is<br />
reached. Then this tiny mass of cells (it can be less than 1 millimeter in diameter) is cut in<strong>to</strong> 20 or so parts,<br />
immersed in<strong>to</strong> a flask with growing solution without agar, so the solution stays liquid. This media for this solution<br />
is usually called “multiplication” formula.<br />
The flasks or tubes are placed on an agita<strong>to</strong>r (an apparatus than either slowly rotates or tilts <strong>to</strong> the left then <strong>to</strong> the<br />
right. The constant movement of the agita<strong>to</strong>r allows the lumps of cells <strong>to</strong> develop and increase in mass but prevents<br />
them from forming roots or leaves.<br />
Once the lumps have sufficiently increased in size they are further cut in<strong>to</strong> small lumps, placed in<strong>to</strong> flasks or<br />
tubes and on the agita<strong>to</strong>r. In this process the original 20 tiny masses may now be 400. At the next subdivision we<br />
may have 8,000.<br />
This process continues until the desired number of lumps has been achieved.<br />
Then the developed lumps are replated in<strong>to</strong> flasks as is done for germinated seeds. From there on the process is<br />
the same as for seeds.<br />
As in seed propagation all these operations require external disinfecting, and working in sterile conditions.<br />
Plants developed from tissue culture, are called mericlones. They usually are very close in appearance (plant and<br />
flowers) <strong>to</strong> the plant from which the original tissue was taken and they are entitled <strong>to</strong> be recognized by the same<br />
variety name as the plant from which the original tissue was excised. So when you see a plant with a name like<br />
Cattleya Irene Finney “Z” it means this plant was propagated through tissue culture, using tissue from Cattleya<br />
Irene Finney ‘Z’.<br />
Stem propagation.<br />
In this technique a flower stem is used for propagation. If we propagated Phalaenopsis in this manner we would<br />
be looking for a flower stem with just the first flower open or with up <strong>to</strong> half the flowers open.<br />
Flower buds nearer the base of the flower stem open first. Below them there will be a number of undeveloped<br />
buds, which we usually refer <strong>to</strong> as “nodes”.<br />
The flower stem is removed from the plant and is externally decontaminated.<br />
The stem is cut about 1 inch above and below the node, then dipped in decontamination solution for 15 <strong>to</strong> 20<br />
minutes.<br />
Then the protective sheath over the node is removed and about 1/8 of an inch is further removed from both ends<br />
of the stem (above and below the node).<br />
The cutting is inserted in the media solution which is in a tube or jar or flask which was previously sterilized<br />
through au<strong>to</strong>claving.<br />
If the operation is successful we may get up <strong>to</strong> 4 plantlets per node.<br />
Obviously this technique only produces a few plants from a flower stem of the original plant. We may get 10 <strong>to</strong><br />
15 stem propagated plants as opposed <strong>to</strong> the thousands we may get through tissue culture.<br />
Because of the limited yield and the labor intensive procedure stem propagated plants tend <strong>to</strong> be much more<br />
expensive than plants propagated through seed or tissue culture.<br />
On the other hand, unless some abhorrent mutation occurs, these plants will be exactly like the plant they were<br />
propagated from.<br />
These plants <strong>to</strong>o are entitled <strong>to</strong> be recognized by the same variety name as the original plant from which the<br />
original tissue was excised.<br />
As with seed propagation and tissue culture all these operations must be conducted in a sterile environment.<br />
Internode propagation<br />
This technique is similar <strong>to</strong> the stem propagation but instead of using a flower stem as the start up point we use<br />
a growth. It is often used with Dendrobiums.<br />
A growth is removed from the plant and is cut in between nodes. The edges are dipped in a fungicide and then<br />
either inserted or laid on sphagnum moss kept moist.
If the operation is successful we may get 1plantlet per node, but usually much less than that as many nodes will<br />
not develop a plantlet.<br />
Still the technique does not require any sophisticated equipment, is inexpensive and can be done practically by<br />
anyone.<br />
These plants <strong>to</strong>o are entitled <strong>to</strong> be recognized by the same variety name as the original plant from which the<br />
growth was removed.<br />
Divisions & back bulbs<br />
Some <strong>orchid</strong>s grow by developing new growth from the base of the plant. After several years they may have 5, 6,<br />
10 or more growths. We may subdivide such plants <strong>to</strong> get two or three out of the original one.<br />
Often the older growth or old pseudobulbs of these plants do not do anything but if we remove them and plant<br />
them separately they will generate new growth.<br />
Again as for the previous methods where plants were propagated by using tissue, or the fower tem, plants resulting<br />
from divisions and backbulbs are also entitled <strong>to</strong> be recognized by the same variety name as the original<br />
plant from which the growth or back bulbs were removed. The resulting plants will be identical <strong>to</strong> the plant we<br />
divided or from which we removed the pseudobulb(s).<br />
Keikis<br />
Some <strong>orchid</strong>s, mostly Dendrobiums, are no<strong>to</strong>rious for producing keikis which is the Hawaiian word for<br />
“babies”.<br />
Occasionally Phalaenopsis will also produce keikis. Some, usually species, do it because it is programmed in<strong>to</strong><br />
their genes, others do it when they are exposed <strong>to</strong> high temperatures while they are developing a flower stem.<br />
Keikis will develop leaves first. Eventually they will develop roots. When roots have reached about an inch in<br />
length we can remove the keiki from the mother plant and plant it in its own container.<br />
Keikis will be identical <strong>to</strong> the plant they were removed from and are also entitled <strong>to</strong> be recognized by the same<br />
variety name, if any, as the plant from which they originated.<br />
Top cuts<br />
Finally, some plants, mostly vandaceous <strong>orchid</strong>s, tend <strong>to</strong> grow very tall. Heights of 4, 5, 6 feet or more are not<br />
unusual, making them difficult <strong>to</strong> handle. These also tend <strong>to</strong> develop new roots along their stem, in between<br />
leaves. These can be divided by<br />
cutting off the <strong>to</strong>p portion of the plant as long as this <strong>to</strong>p portion has at least 2 pairs or roots attached <strong>to</strong> it.<br />
The remaining (bot<strong>to</strong>m) part of the plant will often respond <strong>to</strong> this attack by sending out new shoots from its<br />
base.<br />
Top cuts are of course the same as the plant they were removed from and are also entitled <strong>to</strong> be recognized by<br />
the same variety name, if any, as the plant from which they originated.
2 Potting <strong>Orchids</strong><br />
2.1 Growth pattern of <strong>orchid</strong>s (monopodial, sympodial)<br />
2.2 Roots of <strong>orchid</strong>s<br />
2.3 Containers for growing <strong>orchid</strong>s<br />
2.4 Potting materials<br />
2.5 Our potting mixes<br />
2.6 Potting <strong>orchid</strong>s-general<br />
2.7 Potting monopodial <strong>orchid</strong>s<br />
2.7.1 Potting monopodial <strong>orchid</strong>s in sphagnum moss<br />
2.7.2 Potting monopodial <strong>orchid</strong>s in bark<br />
2.8 Potting sympodial <strong>orchid</strong>s<br />
2.8.1 Potting sympodial <strong>orchid</strong>s in sphagnum moss<br />
2.8.2 Potting sympodial <strong>orchid</strong>s in bark<br />
2.9 Care after repotting <strong>orchid</strong>s<br />
2.1 Growth pattern of <strong>orchid</strong>s<br />
Orchid have two distinct patterns of growth :monopodial & sympodial.<br />
Monopodial <strong>orchid</strong>s, such as Phalaenopsis and Vandas, have a single growth, typically an elongated stem which<br />
may be fairly short (i.e. Phalaenopsis) or reach several feet long like some Vandas, Renantheras or like the liana<br />
like Vanilla.<br />
Sympodial <strong>orchid</strong>s, such as Cattleyas, Oncidiums, Cymbidiums, Paphiopedilums, have several, sometimes<br />
dozens of successive growths.<br />
In sympodial <strong>orchid</strong>s the life of each growth is determinate (meaning it will last 3, 4 or 7 seven years) but the<br />
life of the plants may be, in theory, unlimited. The Manual of Cultivated Orchid Species (by Helmut Bechtel,<br />
Phillip Cribb and Edmund Launert, MIT Press) says : “the longevity of <strong>orchid</strong> plants in cultivation is still something<br />
of a mystery, for several plants in the <strong>orchid</strong> greenhouses at Kew are over 100 years old and are still thriving<br />
and flowering regularly”.<br />
2.2 Roots of <strong>orchid</strong>s<br />
The roots of <strong>orchid</strong>s perform two basic functions, and in some <strong>orchid</strong>s, they perform a third one. First they<br />
secure the plants where they grow. Roots of epiphytic <strong>orchid</strong>s once attached on the bark of the tree they grow<br />
on, or <strong>to</strong> the clay pot they grow in, are nearly impossible <strong>to</strong> detach.<br />
The second function is <strong>to</strong> provide the plant with water and dissolved mineral salts.<br />
Roots of terrestrial <strong>orchid</strong>s are relatively simple. They originate at the base of the stem, they are usually thin,<br />
long, fibrous and rarely branched. Sometimes, as in the case of Paphiopedilums, they are densely haired (or<br />
<strong>to</strong>men<strong>to</strong>se) so that they can absorb moisture from the tinniest particles of growing medium.<br />
Roots of epiphytic <strong>orchid</strong>s tend <strong>to</strong> be more complex, and for good reason, as water supply can be erratic, and<br />
this water supply will often contain very limited amounts of mineral salts.<br />
A distinctive feature of the roots of epiphytic <strong>orchid</strong>s is their silvery <strong>to</strong> gray color. This is due <strong>to</strong> the velamen<br />
which consists of a single or of several layers of epidermal cells. The velamen covers all the root system except<br />
for the short terminal tip of the roots. The role of the velamen is <strong>to</strong> absorb moisture from the ambient<br />
atmosphere, and, may be, <strong>to</strong> protect from cold or heat.<br />
A third quite remarkable function of the roots of epiphytic <strong>orchid</strong>s is their capacity <strong>to</strong> pho<strong>to</strong>synthesize. In some<br />
species the roots have al<strong>to</strong>gether taken this function from the leaves. Genera such as Campylocentrum and<br />
Microcoelia are completely leafless, and in an extreme case, such as the genus Taenuiphylum, roots are flat,<br />
green and look very much like leaves.<br />
Roots of epiphytic <strong>orchid</strong>s are almost constantly exposed <strong>to</strong> the air. And though the ambient humidity may be<br />
high and, in some cases, tropical rains may be a daily event, these roots are never immersed in water, certainly
not for any extensive period of time.<br />
Roots of epiphytic or lithophytic <strong>orchid</strong>s need a lot of air <strong>to</strong> function. Its is extremely important <strong>to</strong> know this as<br />
most <strong>orchid</strong>s are killed because of excessive water (which chases the air).<br />
2.3 Containers / supports for growing <strong>orchid</strong>s<br />
The most common containers / supports for growing <strong>orchid</strong>s are:<br />
Pots<br />
-plastic pots<br />
-clay pots<br />
-<strong>orchid</strong> clay pots<br />
Baskets<br />
-Vanda baskets<br />
-wire baskets<br />
Supports<br />
-cork slabs,<br />
-tree fern plaques,<br />
-pieces of driftwood.<br />
Plastic pots<br />
Most commercial growers use plastic pots because they are inexpensive, they are lighter and they are easier <strong>to</strong><br />
s<strong>to</strong>re; because they hold water for a longer period than other pots / containers, because mineral salts (from water<br />
and fertilizer) will not adhere <strong>to</strong> them, and because roots will not get attached <strong>to</strong> them.<br />
Plastic pots are excellent containers for growing <strong>orchid</strong>s. Their only draw back, is that some plants, notably<br />
Dendrobiums, might get <strong>to</strong>p heavy in them.<br />
Green plastic pots are the ones most commonly used plastic pots. Lately clear plastic pots have become more<br />
widely available. Advocates of clear plastic pots claim the light transmission of clear plastic pots enable roots <strong>to</strong><br />
pho<strong>to</strong>synthesize.<br />
If you are going <strong>to</strong> use plastic pots, look for pots with a fair number of drainage holes ( 4 <strong>to</strong> 8 holes on 3” <strong>to</strong> 4”<br />
pots, 8 <strong>to</strong> 12 holes on 5” <strong>to</strong> 6” pots,...). .<br />
Clay pots<br />
The advantage of clay pots is the stability due <strong>to</strong> their weight and their porosity which allows the potting material<br />
<strong>to</strong> dry faster. Of course, drying faster can also be a disadvantage. A possible disadvantage is that roots tend<br />
<strong>to</strong> attach themselves <strong>to</strong> the pot.<br />
Clay <strong>orchid</strong> pots<br />
Have either holes or slits on their sides <strong>to</strong> allow more air circulation than regular clay pots. As a result, they dry<br />
even faster than regular clay pots.<br />
Vanda baskets<br />
Are used mostly for Vandas and vandaceous <strong>orchid</strong>s, but can be used for most <strong>orchid</strong> genera.<br />
Most Vanda baskets are made of cedar or teak wood. Unfortunately the cedar baskets available <strong>to</strong>day tend <strong>to</strong><br />
decay in a couple of years. Teak baskets are expensive and because teak trees are being depleted it is not<br />
ecologically friendly <strong>to</strong> buy teak baskets. Fortunately plastic Vanda baskets have made their appearance. The<br />
ones I saw (4” and 8”) are made of sturdy plastic that should last forever if we recycle them.<br />
Cork slabs<br />
Are used for mounting <strong>orchid</strong>s. Pieces of cork range can be as small as 2” by 3” or as large as 12” by 24”.<br />
Some <strong>orchid</strong>s will only thrive when mounted on a piece of cork or on a tree fern slab or a piece of driftwood, but<br />
many that grow fine in pots will also thrive on a piece of cork and it makes for a much more natural and interesting<br />
look.<br />
Tree fern plaques<br />
Are flat, and come in different sizes (4” by 4”, 4” by 6”, 8” by 8”,...). Like cork, they are also used <strong>to</strong> mount<br />
<strong>orchid</strong>s. Although easier <strong>to</strong> cut than cork slabs I am not crazy about tree fern slabs because some of them are so<br />
dense they barely absorb any water while other appear <strong>to</strong> fall apart as you handle them.<br />
Driftwood<br />
An alternative for cork that also can make for some very intriguing and interesting “compositions”.
2.4 Potting materials<br />
Understanding the properties of potting materials will help us select the potting material that best meets the<br />
other criterias.<br />
What potting materials for <strong>orchid</strong>s must do is:<br />
1 - hold the plant in place,<br />
2 - hold enough moisture (water) for the needs of this particular <strong>orchid</strong>,<br />
3- provide an environment that will enhance the development of roots (aeration).<br />
Most potting materials for <strong>orchid</strong>s do not provide any nutrients. We add the nutrients in the water via the fertilizers<br />
we use and that’s how they are made available <strong>to</strong> the plants.<br />
There are many potting material for <strong>orchid</strong>s, such as:<br />
• <strong>orchid</strong> bark,<br />
• sphagnum moss,<br />
• tree fern,<br />
• osmunda fiber,<br />
• coconut chunks,<br />
• coconut fiber,<br />
• lava rock,<br />
• charcoal,<br />
• pieces of cork,<br />
• peat moss,<br />
• rockwool, ...<br />
There are many other potting materials. A grower I know in Hawaii uses the shells of macadamia nuts (which he<br />
gets for free), another grower in British Columbia uses straight perlite. I heard of a French grower who uses<br />
straight Styrofoam peanuts and many growers in Thailand use 1/2 shells of immature coconuts,..<br />
Today in the United States the most commonly used potting materials are <strong>orchid</strong> fir bark and sphagnum moss.<br />
Orchid bark<br />
Orchid bark is an excellent material. It is easy <strong>to</strong> use, it will not hold excessive water and, under normal use will<br />
not need <strong>to</strong> be refreshed for about 2 years.<br />
Orchid bark (which usually is the bark from redwood or Douglas fir), comes in 3 sizes (sizes are also referred <strong>to</strong><br />
as ‘grades”): small size (also known as “seedling” size), medium and large (or coarse) size.<br />
The sizes used are mostly the seedling size and the medium size.<br />
Bark is rarely used alone. Most growers add <strong>to</strong> it one or more of the following:<br />
- perlite,<br />
- sponge rock (which is expanded perlite),<br />
- charcoal (horticultural grade),<br />
- sphagnum moss,<br />
- tree fern,<br />
- peat moss,...<br />
Perlite and sponge rock are used <strong>to</strong> create more air space in the mix .<br />
Charcoal is used <strong>to</strong> absorb harmful materials that may be in the water.<br />
Sphagnum or peat moss are used <strong>to</strong> increase the water holding capacity of the mix.<br />
Sphagnum moss<br />
Sphagnum moss (premium grade which is long fibered and completely free of debris and other materials) is an<br />
excellent material which is widely believed <strong>to</strong> have fungicidal properties. It is more expensive than <strong>orchid</strong> bark.<br />
Sphagnum moss holds a lot more water than bark, is not as easy <strong>to</strong> use and needs <strong>to</strong> be refreshed every year.<br />
Sphagnum moss comes mostly in two grades: fine (or seedling grade) and long fibered.
Tree fern<br />
Tree fern, from the roots of a fern called “tree fern”, is an excellent material that is relatively easy <strong>to</strong> use and<br />
will easily stay fresh for 3 years. The material is relatively expensive.<br />
There are 2 varieties of tree fern: one is sort of light brown and flexible, is mostly available in Hawaii and is<br />
called Hawaiian tree fern, also known as “hapu”, the other is dark brown and rigid and comes mostly from<br />
Central America. The latter is what is typically referred <strong>to</strong> as “tree fern” and, unless otherwise noted, when we<br />
mention “tree fern” we mean the rigid one from Central America.<br />
Medium tree fern holds just about as much water as medium fir bark (fine tree fern holds more than fine fir<br />
bark), but by far not as much as sphagnum moss. It is more expensive than <strong>orchid</strong> bark.<br />
Tree fern also comes in 3 sizes: fine (or seedling grade), medium and coarse.<br />
Osmunda fiber<br />
Was a choice material in decades past. Nowadays it is not as readily available and it is expensive. Furthermore,<br />
it comes in relatively large chunks that you have <strong>to</strong> cut in<strong>to</strong> about 1/2” chunks in order <strong>to</strong> use it. Great exercise<br />
for the wrist but who has the time ? Furthermore, when using osmunda fiber you must make sure the fibers are<br />
aligned vertically so as <strong>to</strong> allow the water <strong>to</strong> drain.<br />
Coconut chunks<br />
Coconut has been widely used in Asia where it is readily available and is a renewable resource.<br />
In the last few years it started being used in the US Coconut comes either in chunks (small and medium size) or<br />
in long fibers.<br />
Coconut is more expensive than bark but it will last up <strong>to</strong> 5 years and is relatively easy <strong>to</strong> use.<br />
One drawback of the coconut chunks is that, based on literature we read, it can be very high in sodium when<br />
first used (some say “depending on the source”). As it ages it apparently looses much of its sodium content.<br />
Our experience using coconut chunks as a potting material is limited, but from this limited experience we found<br />
it holds the water much longer than bark and therefore we would suggest caution when using it.<br />
Coconut fiber<br />
Coconut fiber, as far as we know, is not widely used <strong>to</strong> grow <strong>orchid</strong>s. We use a thin layer of it <strong>to</strong> line Vanda and<br />
wire baskets <strong>to</strong> prevent other potting materials from falling out of the basket.<br />
We also use it <strong>to</strong> “stuff ” Vanda baskets when potting vandaceous <strong>orchid</strong>s (Vandas and related) so as <strong>to</strong> hold just<br />
a little bit of moisture and <strong>to</strong> help hold the plant in place. Use it sparingly, and “fluff ” it because if it is <strong>to</strong>o<br />
dense it will stay wet and Vandaceous <strong>orchid</strong>s hate this.<br />
Lava rock<br />
As far as we know it is mostly used by growers in Hawaii where it is plentiful.<br />
We do not use straight lava rock as a potting material. We use a limited amount of lava rock as part of our semiterrestrial<br />
mix (see potting mixes).<br />
Charcoal<br />
In the US charcoal is rarely used as the main or sole ingredient of the potting material. Some growers add charcoal<br />
<strong>to</strong> their potting material because charcoal absorbs <strong>to</strong>xins that may be present in the water and, as Eric A.<br />
Christenson wrote in his book “Phalaenopsis - a monography” charcoal will also absorb <strong>to</strong>xins released by the<br />
roots of plants.<br />
Charcoal does not degrade easily so it will retain it’s ability <strong>to</strong> aerate the potting material. If you are going <strong>to</strong> use<br />
charcoal, make sure <strong>to</strong> only use horticultural grade charcoal.<br />
Pieces or cork / cork from bottles<br />
Cork comes in relatively large pieces (slabs) and <strong>to</strong> use it as a potting material you’ll have <strong>to</strong> cut it <strong>to</strong> useable pieces,<br />
may be about 1/2” in size, which is difficult, and could be dangerous. Same will go for cork from (wine) bottles.<br />
We only use relatively large pieces of cork slabs (2” by 3”, 4” by 6”, 6” by 8”...) <strong>to</strong> mount <strong>orchid</strong>s.<br />
Peat moss<br />
We have no experience at all using this neither as the main ingredient nor as an additive. From what we read<br />
about peat moss it has a high water retention capacity and it does stay relatively intact for several years. Some<br />
growers include it as part of their mix.
Rockwool<br />
Rockwoll is an inert material that looks like dirty cot<strong>to</strong>n. There are 2 varieties of rockwool: one absorbs water,<br />
the other repels water.<br />
Ten years ago or so we used water absorbent rockwool as part of our potting mix but gave up on it because it<br />
holds <strong>to</strong>o much water and was difficult <strong>to</strong> mix. But the worse was its propensity <strong>to</strong> collapse which reduced the<br />
air space in the potting material.<br />
Aliven (man-made clay pellets)<br />
Several years ago we experienced with Aliven because it is inert, practically indestructible and it is easy of use<br />
(we could say the same about lava rock).<br />
At first we thought we had a winner, but as plants stayed longer in it we realized new roots had a pronounced<br />
tendency <strong>to</strong> grow out of the pot and not in it. After a year or so we gave up on it.<br />
2.5 Our potting mixes<br />
We use the following potting mixes and / or potting materials: Mix A holds the most water, mix B a little less<br />
than mix A, mix C a little less than mix B and so on.<br />
Mix A - Sphagnum moss<br />
Mix B - Semi-terrestrial mix<br />
Mix C - Fine bark mix<br />
Mix D - Medium bark mix<br />
Mix E - Medium tree fern<br />
Mix F - Long fibered coconut husk<br />
Mix A - Sphagnum moss<br />
Premium quality, long fibered sphagnum moss, nothing else added.<br />
Repot every year with this mix.<br />
Mix B -Semi - terrestrial mix<br />
The mix consists of -4 parts fine bark,<br />
-1 part sponge rock (= expanded perlite).<br />
-1 part chopped (1/2” <strong>to</strong> 1”) sphagnum moss,<br />
-1 part fine tree fern,<br />
A variation on this mix will include 1 part lava rock or Aliven or a similar material.<br />
Unless specified otherwise (for specific plants), repot every two years with this mix.<br />
Mix C - Fine bark mix<br />
The mix consists of -4 parts fine bark,<br />
-1 part sponge rock (= expanded perlite).<br />
Repot every two years with this mix.<br />
Mix D - Medium bark mix<br />
The mix consists of -4 parts medium bark,<br />
-1 part sponge rock (= expanded perlite).<br />
Repot every two years with this mix.<br />
Mix E - Medium tree fern<br />
This consists of 100 % medium tree fern.<br />
Repot every two <strong>to</strong> three years with this mix.<br />
Mix F - Long fibered coconut husk<br />
This consists of 100 % long fibered coconut husk. Fluff the material before using it because it is <strong>to</strong>o dense as it<br />
comes. Being <strong>to</strong>o dense will reduce air circulation and will hold water for <strong>to</strong>o long.<br />
Repot every three <strong>to</strong> five years with this mix.
We use this long lasting potting material :<br />
- for lining Vandas baskets,<br />
- for lining wire baskets for Stanhopeas or Vandaceous <strong>orchid</strong>s,<br />
- as a backing for some mounted plants,<br />
Lining Vanda or wire baskets with long fibered coconut husks prevents the potting material (which can be<br />
medium bark, medium tree fern, coconut chunks,..) from falling through the openings of the Vanda or the wire<br />
basket. Use the material sparingly.<br />
The composition of our potting mixes is available on a summary chart.<br />
2.6 Potting <strong>orchid</strong>s-general<br />
Potting comprises 2 parts<br />
1 - unpotting the plant from the old container and grooming the plant,<br />
2 - re-potting the plant and staking it if necessary.<br />
Unpotting the plant from the old container<br />
Water the plant first as it makes it easier <strong>to</strong> remove the old potting material.<br />
Retrieve the plant from the pot and remove all the old potting material.<br />
Trim dead roots with sterilized shears or scissors.<br />
You are now ready <strong>to</strong> (re)pot the plant, so let’s see which potting material we’ll use.<br />
Which <strong>orchid</strong>s <strong>to</strong> pot in sphagnum moss<br />
When we mention “sphagnum moss” or “moss” we mean the premium quality long fibered. We do not use the<br />
seedling grade, which <strong>to</strong> our opinion, does not allow for enough air circulation.<br />
As a general rule we use sphagnum moss for potting:<br />
-all Phalaenopsis up <strong>to</strong> pot size<br />
-plastic pot 6”,<br />
-clay pot 7”<br />
-all other young plants up <strong>to</strong> a pot size -plastic pot 2 1/2”<br />
-clay pot 3 1/2”<br />
Mature miniature plants, such as Tolumnia, although potted usually in 2 <strong>to</strong> 3” clay pots, are not young plants<br />
and therefore we do not pot them in moss.<br />
See at the end of this section the chart “Potting Mixes” for which potting mix <strong>to</strong> use for other plants.<br />
2.7 Potting monopodial <strong>orchid</strong>s<br />
2.7.1 Potting Phalaenopsis & other monopodial <strong>orchid</strong>s in sphagnum moss<br />
Place the roots in the pot. The plastic pot size should be just large enough <strong>to</strong> accommodate the roots. If you<br />
use a clay pot, use a pot that’s just one size larger<br />
than the plastic pot, allowing for about 1” of space around the roots, a little more if you use a clay <strong>orchid</strong> pot.<br />
Center the plant and hold it so that the junction of roots and lower leaves is flush with the <strong>to</strong>p of the plastic pot, add<br />
peanuts <strong>to</strong> fill just below the inside rim of the plastic pot. If you are using a clay pot fill about 2/3 of the pot with peanuts.<br />
Fluff the moss and fill with moss <strong>to</strong> the <strong>to</strong>p rim of the pot without pushing <strong>to</strong>o hard on the moss.<br />
While holding the plant from the base (where leaves and roots join), firm the moss down <strong>to</strong> the inside rim of the<br />
pot (if you are using a clay pot, firm the moss down <strong>to</strong> about 1/2” <strong>to</strong> 1” below the rim of the pot).<br />
For best results moss must be well moist (but not dripping wet - if it’s dripping wet squeeze the water out of it).<br />
When placed and firmed in the pot the sphagnum moss should pretty much stay in place. If it does not, then the<br />
moss is <strong>to</strong>o dry.<br />
When done the base of the plant should be just a little higher than the moss so that leaves do not <strong>to</strong>uch the moss<br />
and the <strong>to</strong>p of the roots are just a little bit exposed.<br />
If you were <strong>to</strong> remove the plant from the pot, you should see no more than 1/2” <strong>to</strong> at most 1” of potting material<br />
in a 4” <strong>to</strong> 5” pot.
Trim yellow, shriveled leaves and parts of leaves with spots.<br />
If necessary stake the plan so that it does not wobble. If the plant wobbles the roots will move every time you<br />
water or <strong>to</strong>uch the pot and the roots will have a hard time establishing themselves. We like <strong>to</strong> use a 12 gage galvanized<br />
metal stake folded in two (U shape) <strong>to</strong> hold the plant in place. After two or three months we just pull out<br />
the stakes without disturbing the plant.<br />
2.7.2 Potting Phalaenopsis & other monopodial <strong>orchid</strong>s in bark<br />
Place the roots in the pot. The plastic pot size should be just large enough <strong>to</strong> accommodate the roots plus<br />
about 1/2” space all around them. If you want <strong>to</strong> use a clay pot, use a pot that’s just one size larger than the plastic<br />
pot, allowing for about 1” of space around the roots, a little more if you use a clay <strong>orchid</strong> pot.<br />
Center the plant and hold it so that the junction of roots and lower leaves is flush with the <strong>to</strong>p of the pot, then<br />
place a 1” <strong>to</strong> 2” ( pot size up <strong>to</strong> 5”) or 2” <strong>to</strong> 3” (pot size 6” <strong>to</strong> 7”) layer of Styrofoam peanuts at the base of the<br />
pot, making sure <strong>to</strong> fill in between roots.<br />
Add loosely the bark mix so as <strong>to</strong> fill <strong>to</strong> the <strong>to</strong>p rim of the pot, then tap gently the side of the pot <strong>to</strong> settle the<br />
bark, then gently firm it down a little. Pushing <strong>to</strong>o hard on the bark will crash the roots, so be gentle when<br />
firming it down.<br />
2.8 Potting sympodial <strong>orchid</strong>s<br />
2.8.1 Potting sympodial <strong>orchid</strong>s in sphagnum moss<br />
On some sympodial <strong>orchid</strong>s such as Cymbidiums, Jumeleas, Paphiopedilum, Phragmipedium, ... the new<br />
growth(s) will be very close <strong>to</strong> the base of the old growth(s), forming sort of a circle around the older growth(s).<br />
The potting procedure for these type of young plants is the same as for Phalaenopsis.<br />
But for many sympodial <strong>orchid</strong>s, such as Cattleyas, Dendrobiums, Oncidiums,...the new growth(s) develop<br />
along a rhizome and usually tend <strong>to</strong> grow in the opposite direction of the old growth(s).<br />
The procedure for potting these is the same as for Phalaenopsis except that instead of centering the plant you<br />
want the older portion of the plant as close <strong>to</strong> one edge of the pot as you can get it, leaving room on the opposite<br />
side of the pot for the new growth(s).<br />
We said “usually tend <strong>to</strong> grow on the opposite side” because that’s how they will develop most of the time, but<br />
occasionally the new growth will be more of less adjacent <strong>to</strong> the previous one. Examine how your plant grows<br />
<strong>to</strong> decide where <strong>to</strong> leave room for the new growth <strong>to</strong> develop.<br />
There are several ways <strong>to</strong> distinguish older growth from new growths :<br />
1 - the color of new growth is usually lighter than the color of older growth,<br />
2 - pseudobulbs of new growth are often flat until the (new) growth matures,<br />
3 - the older growth is the smallest in size, and in many cases will be leafless.<br />
When done the base of the plant or the rhizome should be just a little higher than the moss so that leaves do not<br />
<strong>to</strong>uch the moss and the <strong>to</strong>p of the roots are just a little bit exposed.<br />
2.8.2 Potting sympodial <strong>orchid</strong>s in bark<br />
Pots should be large enough <strong>to</strong> accommodate the plant and allow for 1 or 2 years worth of growth (depending on<br />
how frequently you want <strong>to</strong> repot your plants). As for pot type, up <strong>to</strong> 6” we like <strong>to</strong> use Azalea (deep) pots, and<br />
above 6” we prefer <strong>to</strong> use pan (shallow) pots. This is <strong>to</strong> maintain a proper balance between root system and<br />
amount of potting material, so as <strong>to</strong> avoid plants staying wet <strong>to</strong>o long.<br />
On some sympodial <strong>orchid</strong>s such as Cymbidiums, Jumeleas, Paphiopedilum, Phragmipedium,...the new<br />
growth(s) will be very close <strong>to</strong> the base of the old growth(s), forming sort of a circle around the older growth(s).<br />
The potting procedure for these type of young plants is the same as for Phalaenopsis.<br />
But for many sympodial <strong>orchid</strong>s, such as Cattleyas, Dendrobiums, Oncidiums,...the new growth(s) develop<br />
along a rhizome and usually tend <strong>to</strong> grow in the opposite direction of the old growth(s).<br />
The procedure for potting these is the same as for Phalaenopsis except that instead of centering the plant you<br />
want the older portion of the plant as close <strong>to</strong> one edge of the pot as you can get it, leaving room on the opposite<br />
side of the pot for the new growth(s).
We said “usually tend <strong>to</strong> grow on the opposite side” because that’s how they will develop most of the time, but<br />
occasionally the new growth will be more of less<br />
adjacent <strong>to</strong> the previous one. Examine how your plant grows <strong>to</strong> decide where <strong>to</strong> leave room for the new growth<br />
<strong>to</strong> develop.<br />
2.9 Care after repotting<br />
Repotting can be as much of a shock <strong>to</strong> plants as major surgery is <strong>to</strong> humans.<br />
So for a few weeks after repotting a plant you want <strong>to</strong> nurture it a bit.<br />
• Spray (mist) their leaves lightly twice a day for two weeks (healthy plants) <strong>to</strong> four weeks (weak and ailing<br />
plants). Spray early in the day and again no later than mid day (no later than 12 noon in the winter). Add <strong>to</strong><br />
your misting water 2 or 3 drops of Superthrive and 2 or 3 drops of a rooting solution. If you do not have rooting<br />
solution add 2 or 3 drops of a fertilizer high in phosphorous such as .<br />
• For 3 <strong>to</strong> 4 weeks you so place the newly repotted plants at a location where they will be getting less light than<br />
what they usually get. The lower light levels will reduce the stress caused by the repotting shock and will help<br />
the plants recover better and faster.<br />
• Do not water for a week after repotting. Water lightly (just enough <strong>to</strong> get the potting material moist, not<br />
enough for the water <strong>to</strong> run through the drainage holes) a week after repotting, adding <strong>to</strong> your water a few<br />
drops of rooting solution.<br />
• As from a week later water thoroughly once a week.<br />
• Use the rooting solution instead of fertilizer for the first 3 or 4 waterings after repotting.
3 Light levels for growing <strong>orchid</strong>s<br />
3.1 How light is measured/expressed<br />
3.2 Misconceptions about light<br />
3.3 How light diffuses<br />
3.4 How <strong>to</strong> measure light<br />
3.5 What is low light, moderate light and bright light for <strong>orchid</strong>s?<br />
3.6 Where <strong>to</strong> grow your <strong>orchid</strong>s at home<br />
3.7 Impact of light on your <strong>orchid</strong>s<br />
3.8 Light versus direct sunlight<br />
3.9 Growing under lights<br />
3.9.1 Spectrum (colors) of light and it’s impact on plants<br />
3.9.2 Horticultural Vs household lamps<br />
3.9.3 Output of light bulbs<br />
3.9.3.1 Fluorescent lights<br />
3.9.3.2 High intensity lamps<br />
3.9.4 Getting more information about light fixtures<br />
3.1 How is light measured / expressed<br />
Light intensity is measured / expressed in various ways. One of the oldest measures of light is the foot-candle<br />
(abbreviated fc).<br />
A fc is an old English measure. It defines the light projected by a standardized candle over an area of one square<br />
foot from a distance of one foot. Back then, before electricity, that’s how people read, by the light of a candle.<br />
Another way <strong>to</strong> measure light is by Klux (stands for kilo lux or 1,000 lux). The lux (plural luxes, abbreviated lx)<br />
is the International System unit of illumination, equal <strong>to</strong> one lumen per square meter.<br />
One fc is also one lumen but per square foot. One Klux equals approximately 92.3 fcs.<br />
Other methods for measuring light will be in mE/m2 = milli-einsteins per square meter per second, or in<br />
Watts/m2 = watts per square meter,...<br />
Most books about growing <strong>orchid</strong>s refer <strong>to</strong> light levels in fcs, so that’s the measure we’ll use for this chapter.<br />
<strong>Orchids</strong> in the wild are widespread, growing in the dim light of a rain forest or in the bright light of a mountain<br />
slope. Therefore we’ll encounter <strong>orchid</strong>s that need relatively low light conditions, other that need moderate light<br />
and some that need bright light.
3.2 Misconceptions about light.<br />
I often hear people say “I have my <strong>orchid</strong>s in a very bright location, it’s by a north facing window” or “my<br />
<strong>orchid</strong>s get plenty of light, there are in the middle of the room under a skylight”.<br />
Sorry folks but what your plants are getting is what we, humans, consider bright light, but this is far from being<br />
bright light for your plants.<br />
On a bright early September day, at noon, I measured the outside light and the light in a south facing kitchen.<br />
The outside light was 8,000 fcs. The south facing kitchen has a sliding door opening <strong>to</strong> the south. It has a 2 1/2<br />
feet by 5 feet window facing south and it has a 3 feet by 5 feet skylight in it. The walls are light cream and the<br />
floor is light green-white tile. There are no trees or tall buildings <strong>to</strong> reduce the light entering this room. This is a<br />
bright room by any measure.<br />
Here are the results in fcs:<br />
Against the unscreened pane<br />
Against the screened pane<br />
1 foot away (in the sunlight)<br />
2 feet away (in the shade)<br />
3 feet away (in the shade)<br />
4 feet away (in the shade)<br />
10 feet away, under the skylight<br />
By the sliding door<br />
6,000<br />
4,000<br />
3,000<br />
600<br />
500<br />
400<br />
less than 200<br />
3.3 How light diffuses<br />
By the window<br />
6,000<br />
4,000<br />
3,000<br />
600<br />
500<br />
400<br />
less than 200<br />
I also measured the light at a north facing window in the living room. The living room has an true east window,<br />
a south facing sliding door and a large window on the north side. Here are the light levels:<br />
By the east window<br />
By the north windo<br />
Against the unscreened pane<br />
800<br />
400<br />
Against the screened pane<br />
500<br />
200<br />
1 foot away from the window<br />
450<br />
Not measurable<br />
As these measurements show the light levels drops very fast with as you move away from the sources of light<br />
and there is a vast difference in the amount of light depending on the exposure of the window. Remember<br />
none of these windows is shaded by trees or other buildings.<br />
Let me try <strong>to</strong> illustrate how light diffuses with an example. Let’s assume we build a pyramid whose base is 8 feet<br />
by 8 feet and it’s height is 8 feet. The construction is such that no light escapes from the inside and no light penetrates<br />
from the outside.<br />
At the inside <strong>to</strong>p of this pyramid there is a 1,000 watts light bulb emitting approximately 9,230 fcs of light (now<br />
remember that’s the measure of light on a one square foot area at a distance of one foot from the light source).<br />
At the base of the pyramid the area illuminated by this bulb is 8 feet by 8 feet = 64 square feet. As it is the same<br />
amount of light (9,230 fc) that reaches this 64 SF area, the illumination in fc at the base of the pyramid is 144 fc<br />
(9,230 : 64).<br />
Here is another way <strong>to</strong> illustrate this. Let’s assume we have a square basin 1 foot wide and 1 foot tall. The volume<br />
of this bucket is one cubic foot of water. Let’s imagine for the sake of our discussion that the height of the<br />
water can be converted in<strong>to</strong> imaginary foot-candles and that 1 foot of water height equals 1 imaginary foot-candle.<br />
So if we measure the height of the water in the bucket we’ll find it <strong>to</strong> be one foot and therefore one imaginary<br />
foot-candle.<br />
Now let’s pour our bucket of water in a square basin whose sides are two feet wide. The surface of this basin is 4<br />
square feet. Simple math’s will show that the height of the water in this basis will only reach 1/4 a foot which<br />
translates in<strong>to</strong> one quarter of our imaginary foot-candle.<br />
And if we poured this same bucket of water in a square basin whose sides are 3 feet wide, thus with a square<br />
surface of 9 square feet, the height of the water will only reach 1/9 of a foot which translates in<strong>to</strong> 1/9 of our<br />
imaginary foot-candle.
Light, like the water in our basin, will fill all the available space at any given area. Since the <strong>to</strong>tal amount of<br />
light is the same at any given area, the further away we are from the light source, the larger the illuminated area<br />
is and the less amount of light will fall on any given square foot of area.<br />
3.4 How <strong>to</strong> measure light<br />
You can measure light with a light meter. Good ones are available between $ 80.00 and $ 150.00. Some measure<br />
light in foot-candles and others in luxes of Klux’s<br />
You can also use a 35 mm camera <strong>to</strong> measure light. Here is how <strong>to</strong> do it:<br />
• Set the camera at 25 ASA.<br />
• Set the shutter speed at 1/60 of a second.<br />
• Place a white sheet of paper where the leaves of the plants would be.<br />
• Focus on the white sheet of paper from a distance of 1 foot.<br />
• Make a note of the f/s<strong>to</strong>p shown in the viewfinder.<br />
Here are the approximate foot candles corresponding <strong>to</strong> various f/s<strong>to</strong>ps:<br />
f/2 = 100 fc<br />
f/2.8 = 200 fc<br />
f/4 = 375 fc<br />
f/5.6 = 750 fc<br />
f/8 = 1,500 fc<br />
f/11 = 2,800 fc<br />
f/16 = 5,000 fc.<br />
Remember the maximum light should be at noon on a bright summer day.<br />
3.5 What is low light, moderate light and bright light for <strong>orchid</strong>s ?<br />
Let’s start with the maximum light : at noon, on a bright, cloudless summer day, the light level outdoors (in the<br />
northeast) will <strong>to</strong>p 10,000 fc.<br />
We usually consider the light in a supermarket <strong>to</strong> be bright. If we measured that light level with a light meter<br />
we’ll find it’s intensity is about 200 <strong>to</strong> 300 fc, and for us, humans, these 200 or 300 fc of light intensity in the<br />
supermarket are quite comfortable.<br />
But 200 <strong>to</strong> 300 fcs of light is just a pittance for <strong>orchid</strong>s.<br />
To grow and bloom properly :<br />
Low light <strong>orchid</strong>s need<br />
Moderate light <strong>orchid</strong>s need<br />
Low end<br />
1,000 fc<br />
1,500 fc<br />
High end<br />
1,500 fc<br />
3,000 fc<br />
High light <strong>orchid</strong>s need<br />
3,000 fc<br />
4,500 fc.<br />
Please keep in mind these levels of light are for mature plants and the maximum light is for a limited time at the<br />
brightest moment of the day (noon in a bright, cloudless, summer day).<br />
Please also keep in mind you can acclimate some of your <strong>orchid</strong>s <strong>to</strong> grow a little outside of these ranges, within<br />
reason of course.<br />
The book “An Introduction <strong>to</strong> <strong>Orchids</strong> - A <strong>Guide</strong> <strong>to</strong> the Growing and Breeding of <strong>Orchids</strong>” published by The<br />
South Florida Orchid Society(Tel 305-226-4757) and the book “All About <strong>Orchids</strong>” published by Ortho Books<br />
both have very clear charts about light requirements of <strong>orchid</strong>s.
3.6 Where <strong>to</strong> grow you <strong>orchid</strong>s at home<br />
In practical terms what this means is that <strong>to</strong> provide the minimum light our <strong>orchid</strong>s need <strong>to</strong> grow and bloom<br />
we’ll have <strong>to</strong> grow them :<br />
Low light <strong>orchid</strong>s<br />
Medium light <strong>orchid</strong>s<br />
High light <strong>orchid</strong>s<br />
-on the windowsill of an east window<br />
-or within 1 foot of a west windowsill<br />
-or within 2 feet of a south windowsill<br />
-or within 1 foot of a south windowsill if it is shaded by other plants or by shade.<br />
-on the windowsill of a west window<br />
-within a foot of a south windowsill<br />
-on the windowsill or within a foot of a south windowsill,<br />
(as long as they do not get direct sun in the middle of the day).<br />
Please keep in mind we are talking about windows that are not shaded by trees or other buildings.<br />
3.7 Impact of light on your <strong>orchid</strong>s<br />
Your <strong>orchid</strong>s will, <strong>to</strong> some degree, adapt <strong>to</strong> their environment. You may be able <strong>to</strong> coerce a medium light plant<br />
<strong>to</strong> grow and bloom on a bright east windowsill but you’ll have a real hard time blooming a high light plant on an<br />
east windowsill and very few, if any, will bloom on a north windowsill.<br />
<strong>Orchids</strong> will <strong>to</strong>lerate levels of light on the higher end of their range provided the plant receives more water<br />
(more frequent watering), more fertilizer and, if possible, better air movement <strong>to</strong> keep their leaves a little cooler.<br />
When we say more frequent watering we mean maybe every five days or so instead of every seven days, not<br />
every other day instead of every seven days.<br />
This does not mean you should subject your plants <strong>to</strong> excessive light. If your <strong>orchid</strong>s get <strong>to</strong>o much light and not<br />
enough water and fertilizer, they will be stressed.<br />
Stressed (weakened) plants have less defenses against pests and diseases the same way as weakened humans<br />
have.<br />
Visible signs of stress are shriveling pseudobulbs and / or leaves, drying buds, prematurely wilting flowers,...<br />
Note that this kind of stress can also result from unproper potting, decaying potting material, insufficient watering,....<br />
Watch the foliage of your plants. If the leaves stay green, are crisp and firm, then the light is probably right.<br />
If the foliage is dark green, then the light is <strong>to</strong>o low.<br />
If the foliage shows purplish marks or coloration, then the light is probably <strong>to</strong>o high.<br />
Sometimes if the light is <strong>to</strong>o high the tips of the leaves will dry up.<br />
3.8 Light versus direct sunlight<br />
Very few <strong>orchid</strong>s will <strong>to</strong>lerate direct sunlight, except maybe for an hour or <strong>to</strong>o after sunrise and an hour or two<br />
before sunset.<br />
If you grow your <strong>orchid</strong>s at a south or southeast or southwest location, in a sunroom or in a greenhouse, you’ll<br />
have <strong>to</strong> provide some shade, at least for the brightest part of the day.<br />
Surrounding trees or tall buildings may provide enough shade, sometimes <strong>to</strong>o much shade.<br />
And remember, there is a substantial reduction in the light from summer <strong>to</strong> fall <strong>to</strong> winter. Provide more light /<br />
less shade as from mid Oc<strong>to</strong>ber <strong>to</strong> mid February <strong>to</strong> compensate for this natural reduction in light.<br />
Finally remember that although plants will adapt <strong>to</strong> changing environments, they will adapt better, with less<br />
stress if you gradually ease in<strong>to</strong> the new conditions (such as summering them in bright outdoors light).
3.9 Growing under lights<br />
My personal experience is limited as the only plants I grow under lights are my flasks, but here is some information<br />
<strong>to</strong> get you started.<br />
3.9.1 Spectrum (colors) of light and it’s impact on plants<br />
If you look at a rainbow which diffracts the components of light you’ll see the various colors of the spectrum of<br />
light.<br />
Natural light comprises ultra-violet, violet, blue, green, yellow, orange, red and far-red light. And there also is<br />
invisible infra-red light.<br />
To us, humans, the green and yellow parts of light are what is important for our vision, but these colors are not<br />
that important <strong>to</strong> plants.<br />
For plants, blue, red, far red and infra-red light are the important parts of light.<br />
The blue and red rays of light are necessary for plants <strong>to</strong> pho<strong>to</strong>synthesize.<br />
Red light affects maturation, ripening and dormancy of plants. Far red is necessary for plants <strong>to</strong> grow. Far red<br />
and infra-red affect cell activity, stimulate plant growth and development of new leaves and roots.<br />
3.9.2 Horticultural Vs household lamps<br />
If we plan on growing under lights we have <strong>to</strong> pay attention <strong>to</strong> the spectrum of light emitted by the lamps.<br />
Horticultural lamps have been devised <strong>to</strong> meet as best as possible the types of light necessary for plant development<br />
which of course is not true for lamps developed for human use as our light needs are not the same.<br />
Horticultural lights are available as fluorescent lights and bulbs.<br />
3.9.3 Output of light bulbs<br />
3.9.3.1 Fluorescent lights<br />
Fluorescent lights are mostly rated in the 20 <strong>to</strong> 40 watts which translates in<strong>to</strong> something like 185 <strong>to</strong> 370 fc of<br />
light.<br />
Using several fixtures <strong>to</strong>gether will barely produce enough light <strong>to</strong> grow low light <strong>orchid</strong>s (Phalaenopsis, mottled<br />
leafed Paphiopedilums,...) and then only if the lamps are set only 8” <strong>to</strong> maximum 12” above the foliage.<br />
3.9.3.2 High intensity lamps<br />
As their name indicate these lamps emit substantially more light than fluorescent lights. There are lamps of 100,<br />
250, 400, 600 and even 1,000 watts, emitting anywhere from 1,000 <strong>to</strong> over 9,000 fc.<br />
These bulb lamps require special lighting fixtures that can cost anywhere from $ 150 <strong>to</strong> over $ 500.<br />
Replacement bulbs cost anywhere from $ 35 or so for a 100 watt lamp <strong>to</strong> over $ 100 for a 600 watt lamp. Most<br />
of them are rated for 10,000 hours of use which at 14 hours per day will last more than 2 years, so the cost of a<br />
600 watt bulb is something like<br />
$ 0.15 per day)<br />
There are several brands available (HydroFarm, Sun Systems, Philips Lightning,...).<br />
These fixtures can be combined with a rail system which moves the fixtures back and forth on a straight line or<br />
that rotates the fixture allowing a greater growing area.<br />
Keep in mind the properties of light : at 2’ from the lamp you’ll get 1/4 the light emitted by the lamp and at 3’<br />
you’ll get 1/9 of the light emitted by the lamp.<br />
Many people have great success growing under lights, in poorly lightly rooms, in basements, ...<br />
The biggest challenge of growing under light is managing the day & night temperatures, the humidity and the<br />
air movement which is necessary <strong>to</strong> prevent hot spots on the leaves.
3.9.4 Getting more information about light fixtures<br />
Some of the information provided above was derived from the book “Growing <strong>Orchids</strong> Under Light” (by<br />
Charles Marden Fitch, published by the American Orchid Society, Tel 561-404-2000, web: <strong>orchid</strong>web.com)<br />
which I suggest you buy if you are interested in growing under lights.<br />
Also you may want <strong>to</strong> ask for the Charley’s Greenhouse and Garden catalog ( Tel 800-322-4707, web :<br />
charleysgreenhouse.com) or for the Worm’s Way catalog (800-274-9676, web : wormsway.com) as both feature<br />
an extensive line of horticultural lights and light fixtures.
4 Temperatures for growing <strong>orchid</strong>s<br />
In nature <strong>orchid</strong>s inhabit various habitats, from low land rain forests <strong>to</strong> mountain slopes, <strong>to</strong> swampy areas.<br />
Therefore we can expect some <strong>orchid</strong>s <strong>to</strong> need the warm conditions of a tropical rain forest, others <strong>to</strong> need the<br />
cool conditions of a slope on the foothills of mountains and yet others <strong>to</strong> have needs somewhere in between.<br />
<strong>Orchids</strong> are classified in 3 temperature groups: <strong>orchid</strong>s that require cool temperatures, other that require intermediate<br />
temperatures or others that need warm temperatures.<br />
Here are the temperature ranges for the three groups, and please don’t hold me <strong>to</strong> the degree, as you’ll most<br />
probably see different ranges somewhere else:<br />
Day time Night time<br />
Warm growing <strong>orchid</strong>s<br />
Intermediate growing <strong>orchid</strong>s<br />
Cool growing <strong>orchid</strong>s<br />
Winter<br />
70<br />
65<br />
60<br />
Summer<br />
85<br />
80<br />
75<br />
Winter<br />
60<br />
55<br />
50<br />
Summer<br />
75<br />
70<br />
65<br />
Please notice the difference between day time and night time temperatures. In the natural world it is, most of<br />
the time, warmer in the day and cooler at night.<br />
So when you grow your <strong>orchid</strong>s keep this in mind, especially if you grow them in a bathroom which many of us,<br />
in the winter, tend <strong>to</strong> warm in the morning, then let it cool during the day, then warm it again at night.<br />
But remember these temperatures are ideal ranges and, within reason, you can acclimate your <strong>orchid</strong>s <strong>to</strong> grow<br />
pretty well a few degrees outside of these ranges.<br />
Your warm growing <strong>orchid</strong>s will not die if they are subjected <strong>to</strong> day time temperatures of 90 degrees for a few<br />
days or <strong>to</strong> 55 degrees for a few nights. But at these temperature levels your <strong>orchid</strong>s will s<strong>to</strong>p growing and will<br />
become more susceptible <strong>to</strong> insects and diseases, because there will be under stress.
5.1 How much humidity<br />
5.2 Increasing your humidity<br />
5 Humidity levels for growing <strong>orchid</strong>s<br />
5.1 How much humidity ?<br />
Most <strong>orchid</strong>s require 60 % <strong>to</strong> 80 % humidity. These humidity levels are necessary for the plants <strong>to</strong> perform at<br />
their best and reward you with blooms that stay perfect for the longest possible time.<br />
Although these levels may appear high, they are in fact well within the comfort zone for people which is 40 %<br />
<strong>to</strong> 70 % relative humidity.<br />
In the summer time the natural humidity is usually sufficient <strong>to</strong> meet the needs of your plants, except on bright,<br />
sunny, dry days.<br />
Air conditioning in the summer and artificial heat in the winter, especially from forced air heating and electrical<br />
baseboard heating, will dry the air well below the need of your <strong>orchid</strong>s.<br />
Plants placed in the path of air conditioning or in the path of forced air heating or next <strong>to</strong> a radia<strong>to</strong>r or next <strong>to</strong> a<br />
heat source such as a refrigera<strong>to</strong>r can get quickly desiccated, loose their buds and even their leaves in just a few<br />
days.<br />
Consider investing a few dollars in a hygrometer <strong>to</strong> help you evaluate your conditions.<br />
5.2 Increasing humidity around your plants<br />
If your humidity levels are consistently <strong>to</strong>o low, consider buying a humidifier. A cool mist humidifier can cost<br />
as low as $ 20 <strong>to</strong> $ 25 and will help considerably in maintaining the health of your plants.<br />
Another way of increasing humidity is by setting your plants on trays filled with pebbles or gravel and with<br />
water, as long as the plants are not in contact with the water.<br />
For this <strong>to</strong> be effective the trays must be wide enough so that the leaves of your plants are over the tray (from<br />
where the humidity will raise).<br />
A tray for a single plant will not be of much help as the little humidity rising from it will disperse very fast.<br />
Ideally you want <strong>to</strong> have a dozen or more plants grouped <strong>to</strong>gether as they will create a micro climate with higher<br />
levels of humidity.<br />
In my opinion, the humidifier is the better solution. But if you use one make sure the mist does not blow directly<br />
on your plants as this will eventually wet them and promote bacteria and fungus growth that may well kill your<br />
plants.
6 Fertilizing <strong>orchid</strong>s<br />
6.1 Introduction<br />
6.2 Contents of fertilizers<br />
6.3 Organic vs non organic fertilizers<br />
6.4 Which fertilizers should we use ?<br />
6.5 Should we use the same amount of fertilizer year round ?<br />
6.6 Vitamins, hormones and other additives<br />
6.7 Determining how much fertilizer <strong>to</strong> use in a gallon of water.<br />
6.1 Introduction<br />
When I started growing <strong>orchid</strong>s I bought a few books <strong>to</strong> learn about their culture.<br />
What I unders<strong>to</strong>od about fertilizing was :<br />
- fertilize with high nitrogen plants that are potted in bark,<br />
- fertilize with a balance fertilizer plants that are potted in other media.<br />
- use a high phosphorous fertilizer <strong>to</strong> promote flowering & root formation.<br />
Recommended dosage was 200 PPM nitrogen (for plants in bark).<br />
Some of the questions that came <strong>to</strong> mind were :<br />
- what PPM nitrogen for plants in media other than bark ?<br />
- should the fertilizer dosage be the same year round ?<br />
Then as I read more and more about <strong>orchid</strong>s and fertilizing I started being confronted with more issues :<br />
- TDS (<strong>to</strong>tal dissolved solids)<br />
- PH.<br />
And I heard that some growers recommended the use of Epsom salts, the occasional use of a fertilizer called<br />
Mag Pro, the application in the summer of another fertilizer, Peter’s Cal Nitrate, and yet another fertilizer,<br />
Peter’s Plant Starter during potting,...<br />
At times I got thoroughly confused.<br />
6.2 Contents of fertilizers<br />
All fertilizers contain as principal ingredients Nitrogen, Phosphorous and Potassium, which are commonly<br />
referred <strong>to</strong> as N-P-K.<br />
The percent of these elements are shown on the fertilizer container as 3 numbers separated by dashes, always in<br />
the order N-P-K. For example: 30-10-10, 3-12-6.<br />
In a 30-10-10 formulation, 30 % of the contents are Nitrogen, 10 % are Phosphorous and 10 % are Potassium.<br />
In a 3-12-6 fertilizer, 3% of the contents are Nitrogen, 12% are Phosphorous and 6 % are Potassium.<br />
Nitrogen fertilizer is derived either from urea, ammonia or from nitrates. Nitrogen derived from urea is not<br />
readily available <strong>to</strong> <strong>orchid</strong> plants, therefore the Nitrogen in the fertilizers we use must be derived from ammonia<br />
or nitrates, not from urea.<br />
Fertilizers are basically made of minerals which are an essential ingredient of proteins. All living things need<br />
minerals. We, humans, find many of the minerals we need in fruits and vegetables, in meat, fish, vitamins...<br />
Plants also need minerals and that’s what fertilizers will provide.<br />
Nitrogen<br />
Is an essential element for the chlorophyllian function, that is for the leaves <strong>to</strong> convert light and nutrients in<strong>to</strong><br />
carbohydrates.<br />
Nitrogen is necessary for the plant <strong>to</strong> grow. But excess nitrogen will cause plants <strong>to</strong> grow excessively in size<br />
and may delay flowering ( think of those Vandas ! ).
On the other hand nitrogen deficiency will result in stunted plants.<br />
A recent study by Dr. Yin-Tung Wand of Texas A & M University suggests that “under severe nitrogen<br />
deficiency, the proteins in the lower leaves are digested and the nitrogen is transferred out of the older leaves<br />
in<strong>to</strong> the younger upper leaves (note : of Phalaenopsis). As a result some of the lower leaves start turning yellow<br />
and eventually fall off”.<br />
Phosphorous<br />
Is believed <strong>to</strong> regulate many activities.<br />
It is necessary for the formation of cells, it promotes root growth, it induces and stimulates flowering.<br />
Deficiency is phosphorous will also result in stunted plants, with dark green leaves.<br />
Potassium<br />
Is necessary for healthy growth. Deficiency may result in dwarfness.<br />
Micronutrients<br />
Besides the essential elements (Nitrogen, Phosphorous and Potassium), plants need other minerals such as calcium,<br />
magnesium, iron, manganese,...usually referred <strong>to</strong> as “trace elements” or “micronutrients” because plants<br />
need them in much lower concentrations than Nitrogen, Phosphorous or Potassium.<br />
An ideal fertilizer is one than contains the essential elements and all the micronutrients plants need.<br />
6.3 Organic vs. inorganic fertilizers<br />
Organic fertilizers such as guano and cow manure must be decomposed by bacteria before the nutrients they<br />
contain can be absorbed by plants (the same applies <strong>to</strong> nitrogen from urea).<br />
Decomposition does not occur readily in the type of potting materials used for growing <strong>orchid</strong>s, therefore<br />
organic fertilizers are not suited for <strong>orchid</strong>s.<br />
Also, unprocessed organic fertilizers can host diseases that will affect our plants.<br />
For these reasons, we use, as our basic fertilizers, inorganic fertilizers.<br />
They may be benefits in an occasional application of organic fertilizers such as fish emulsion, but we are not<br />
experienced in their use or effects, therefore we have not included them in our regular fertilizer program.<br />
6.4 Which fertilizer(s) should we use ?<br />
I don’t know how many different formulas of fertilizers there are, but there are a lot. So which fertilizer(s)<br />
should we use ?<br />
Fertilizer chart 1<br />
Here is a chart of the fertilizers we are using in 2002.<br />
As you can see we basically alternate between high nitrogen (10 - 5 -5 ), high phosphorous ( 3 - 12 - 6 ) and balanced<br />
( 7 - 7 - 7 ) fertilizers.<br />
In the beginning of the summer we make 2 applications of 15 - 0 - 0 for additional calcium, and in the summer<br />
time we use more frequently the high nitrogen.<br />
But this is only part of the s<strong>to</strong>ry.<br />
6.5 Should we use the same amount of fertilizer year round ?<br />
Fertilizer chart 2<br />
Because one of the other questions in our mind was should we give our plants the same amount of fertilizer year<br />
round ? Do they need the same amount when they get 14 hours of strong light as when they get 8 hours of low<br />
light ?<br />
I do not remember getting or finding a clear answer <strong>to</strong> this question, but it seems logical <strong>to</strong> me that <strong>orchid</strong>s (and<br />
all plants) could not possibly use the same amount of nutrients on a short winter day as on a long, sunny, summer<br />
day.<br />
We found in the August 1998 issue of the magazine Greenhouse Product News a table of illumination, by<br />
month, for the Northeast. We adjusted this table <strong>to</strong> a weekly schedule and used it <strong>to</strong> determine the amounts of<br />
fertilizer we should give our plants. This is what Fertilizer chart 2 shows.
6.6 Hormones, vitamins and other additives <strong>to</strong> the water<br />
We can not talk about fertilizers without mentioning some other useful additives.<br />
Superthrive<br />
Makers of Superthrive claim their product achieves miracles. We do not know from first hand experience but we<br />
hear from a lot of people that it is very beneficial.<br />
Robert Fuchs, a commercial grower in Florida, claims that continuous use can cause mutations, so he limits it’s<br />
use <strong>to</strong> once a month application.<br />
Pro-Tekt<br />
Consists of 3.7 % soluble potash and 7.8 % silicon derived from potassium silicate.<br />
Field tests have evidenced silicon improves heat & drought <strong>to</strong>lerance.<br />
In addition Dyna Grow (manufacturer of Pro-Tekt) claims it increases resistance <strong>to</strong> environmental stress,<br />
enhances healthier, stronger growth, and produces hardier plants.<br />
Considering several field tests confirm the better results achieved when adding silicon, we made it part of our<br />
fertilizer program.<br />
KLN<br />
A rooting hormone that was developed by Dyna Grow <strong>to</strong> promote root formation on cuttings.<br />
Dave Neil of Dyna Grow recommends <strong>to</strong> use it for 3 waterings after repotting plants.<br />
He also recommends <strong>to</strong> use it monthly as a maintenance <strong>to</strong> promote stronger root growth.<br />
6.7 Determining how much fertilizer <strong>to</strong> use in a gallon of water.<br />
But how much fertilizer should we put in a gallon of water.<br />
This depends on what kind of nitrogen PPM we want <strong>to</strong> achieve.<br />
Here is how <strong>to</strong> calculate the amount of fertilizer <strong>to</strong> add <strong>to</strong> 1 gallon of water in a watering can:<br />
A-Determine the desired nitrogen PPM. For example:<br />
(PPM = parts per million)<br />
B-Find out the % nitrogen in the fertilizer<br />
As in Dyna Grow 10-5-5<br />
C-Number of oz in a gallon<br />
( we started saying this calculation was for one gallon of water)<br />
D-# of oz of fertilizer required per gallon of water is<br />
=A divided by B : 100 / 0.10 or 200 / 0.10<br />
further divided by 1,000,000 (<strong>to</strong> get Parts Per Million)<br />
multiplied by C (the number of oz in a gallon).<br />
Of course an easy way is just <strong>to</strong> follow the instructions on the fertilizer container.<br />
If you decide <strong>to</strong> follow the instructions on the fertilizer and if they give you a range, such as 1/4 teaspoon <strong>to</strong> 1/2<br />
a teaspon per gallon, then use the higher dosage in the summer and the lower one in the winter.<br />
100<br />
10 %<br />
128<br />
0.128<br />
200<br />
10 %<br />
128<br />
0.25
7 Watering <strong>orchid</strong>s<br />
7.1 Quality of water<br />
7.2 How often <strong>to</strong> water<br />
7.3 How and when <strong>to</strong> water your <strong>orchid</strong>s<br />
7.4 Influence of PH on nutrient availability.<br />
7.5 How <strong>to</strong> adjust the PH of your watering solution<br />
7.6 The final word about fertilizing<br />
7.1 Quality of water<br />
The quality of your water is extremely important for good culture. In nature plants are drenched by rain water.<br />
Rain water results from evaporated water and unless it is heavily polluted (like acid rain), that water is very<br />
pure.<br />
Rain water is slightly acidic with a PH fac<strong>to</strong>r of 6.4 <strong>to</strong> 6.8.<br />
Tap water is usually quite acceptable.<br />
Well water is acceptable if its content in mineral salts is below 120. Hard water (water with mineral contents<br />
above 120 PPM) will create hard deposits on the leaves of plants. This may clog the pores on the leaves of<br />
plants and reduce perspiration. If your water is hard it may be beneficial <strong>to</strong> periodically (once <strong>to</strong> twice a year)<br />
clean the leaves with distilled water.<br />
Be careful with water that was softened. There are 2 basic products for softening water: salt and potassium<br />
chloride. Salt adds sodium <strong>to</strong> the water and, over the long term, this can be deadly <strong>to</strong> your plants. Potassium<br />
chloride will not harm the plants.<br />
The best water is water processed through a reverse osmosis system which will remove most of the minerals<br />
from the water. Our well water has over 1,000 PPM (or TDS - Total Dissolved Solids) of minerals in it (calcium,<br />
...). We soften it first then we process it with a reverse osmosis (R.O.) system. The processed water has a mineral<br />
content of less than 20 PPM. (Note : if you use an R. O. system then softening the water with salt is fine<br />
because the R. O. process will eliminate practically all the sodium).<br />
A small home R. O. system producing 30 gallons of water per day costs from $ 150 <strong>to</strong> $ 300 (Nature’s Way -<br />
800-780-2320). Nature’s Way offered these systems on sale in September for $ 119 instead of $ 142.50 and $<br />
279 instead of $ 329.00.<br />
I am not familiar with Nature’s Way system. Our commercial system can produce 1,500 gallons per day. The<br />
processed water is s<strong>to</strong>red in 1,000 gallon tank and must be pressurized before we are able <strong>to</strong> use it. I just mention<br />
this <strong>to</strong> make you aware that you might need something <strong>to</strong> s<strong>to</strong>ring the water if you consider an R. O. system.<br />
7.2 How often <strong>to</strong> water<br />
Here are some general rules for potted plants :<br />
• The potting material should never be soggy. Water potted plants sufficiently <strong>to</strong> prevent them from becoming<br />
bone dry.<br />
• In general water once a week, but be aware that small pots (5” or less) need more frequent watering than large<br />
pots (6” or more).<br />
• Remember that different potting materials and different size potting materials will dry at different rates.<br />
• Also remember that clay pots will evaporate more water than plastic pots and, everything being equal, will dry<br />
faster than plastic pots.<br />
• And remember that clay <strong>orchid</strong> pots, because of their openings, will dry out faster than regular clay pots.<br />
• Conditions are different from room <strong>to</strong> room. If you move your plants, observe them <strong>to</strong> see if your watering<br />
needs adjustment.<br />
• If you place plants in decorative containers (china pot or decorative basket) <strong>to</strong> enjoy them while they are in<br />
bloom, keep in mind this will very probably slow down the evaporation of water and plants will stay wet for a<br />
longer time.
• Finally temperatures, light air conditioning and heating will affect how fast the potting material dries out. Be<br />
ready <strong>to</strong> adjust your watering habits as the season changes, especially from spring <strong>to</strong> summer and from fall <strong>to</strong><br />
winter.<br />
7.3 When and how <strong>to</strong> water your <strong>orchid</strong>s<br />
No matter how careful you are when watering, some water may and will get in between leaves or new growth. If<br />
this water stays there overnight, when temperatures become cooler, it may promote the growth of bacteria and<br />
fungi that may kill your <strong>orchid</strong>s or the new growth of your <strong>orchid</strong>s. To reduce risks of this happening you<br />
should adopt sound watering practices.<br />
• Water only on sunny days. If the weather is cool, cloudy or rainy, you’ll be much better off waiting a day or<br />
two before watering.<br />
• Water early in the day. This will allow any water that got in between leaves or new growth <strong>to</strong> evaporate before<br />
nightfall. In our greenhouses we s<strong>to</strong>p watering at 2 PM in the summer, at 12 noon in the winter and at 1 PM in<br />
the spring and fall.<br />
• Water your plants with room temperature or lukewarm water as a difference of 10 degrees or more between the<br />
temperature of the water and the room temperature may cause injuries <strong>to</strong> the plants.<br />
• Water from the <strong>to</strong>p till the water runs freely through the drainage holes or immerse the plant in water up <strong>to</strong><br />
1/2” or so below the rim and let it absorb water for 10 minutes or so.<br />
Wipe out any water that splashed on the leaves or in between the leaves. Using a straw is a convenient way of<br />
focusing the flow of air <strong>to</strong> blow out water from in between leaves.<br />
7.4 Influence of PH on nutrient availability.<br />
So far we discussed fertilizers, the proper dosage of fertilizers and proper watering, but giving the proper fertilizer<br />
in the proper dosage is only part of the issue. We need <strong>to</strong> make sure the nutrients are made available for the<br />
plants <strong>to</strong> use.<br />
Nutrient availability <strong>to</strong> plants is affected by PH levels. See chart on page 15 of “An introduction <strong>to</strong> <strong>Orchids</strong>”<br />
published by the South Florida Orchid Society.<br />
As an example, Phosphorous is practically not available <strong>to</strong> plants in the PH range of 7.0 <strong>to</strong> 8.5. Availability of<br />
the trace element Manganese is mostly available between a PH level of 4.0 <strong>to</strong> 5.5. Boron between a level PH of<br />
4.5 <strong>to</strong> 6.0.<br />
The above mentioned chart (produced by Michigan State University) shows that most nutrients are available at<br />
their optimal level between a PH level of 5.0 <strong>to</strong> 6.0.<br />
An article in the fall 1997 issue of Greenhouse Grower, although not about <strong>orchid</strong>s, states: “When the PH of the<br />
media is <strong>to</strong>o high, micronutrient deficiencies can be a problem. If the PH is <strong>to</strong>o low, micronutrients become<br />
more available and can lead <strong>to</strong> micronutrients <strong>to</strong>xicity in some crops.”<br />
Even if we started with water with an acceptable PH, the PH will change, up or down, depending on the additives<br />
(fertilizer, root solution, ....) we used. So, after we added all additives, we must adjust our PH <strong>to</strong> a level<br />
that will make these nutrients and other additives available for the plants <strong>to</strong> use.<br />
Most <strong>orchid</strong> sources recommend a PH between 5.5 and 6.5 for <strong>orchid</strong>s and that’s what we aim at after adding<br />
nutrients and / or other additives ( i.e. Zero<strong>to</strong>l, Protekt,...).<br />
7.5 How <strong>to</strong> adjust the PH of your watering solution<br />
First of course you have <strong>to</strong> have a way <strong>to</strong> measure the PH of the water. This is done with a PH meter which you<br />
immerse in<strong>to</strong> the (well) stirred water containing all your additives. A PH meter costs from about $ 65 <strong>to</strong> over $<br />
100.<br />
Two products are available for PH adjustment from Growth Products in White Plains, NY (800-648-7626). PH<br />
booster (0-0-25 liquid potassium) raises the PH while Citric Acid Solution reduces the PH. Go slow ! a few<br />
drops in a gallon can make quite a difference !
7.6 The final word about fertilizing<br />
The final word about fertilizers is from Rebecca Tyson Northen in her book Home <strong>orchid</strong> growing :<br />
“After trying several (fertilizers) on your own plants, you yourself may come <strong>to</strong> have a preference for a certain<br />
one. This is good. Is shows that all is in rapport between you and your plants.”
8.1 Prevention, the best defense<br />
8.2 Pests that may affect your <strong>orchid</strong>s<br />
8.3 Treating insects with an insecticide.<br />
8.4 Making sure the treatment is effective<br />
8.5 Diseases<br />
8 Pests and diseases<br />
8.1 Prevention, the best defense<br />
The best defense against pests and diseases is growing healthy plants through sound culture and proper sanitation.<br />
But even so, once in a while you may have <strong>to</strong> deal with pests.<br />
Pests<br />
Fortunately not <strong>to</strong>o many pests will affect your <strong>orchid</strong>s, but some of them will take determination <strong>to</strong> get rid of.<br />
The insects that may affect your <strong>orchid</strong>s are mostly mealybugs, scale, aphids, fungus gnats, spider mites, thrips<br />
and slugs / snails.<br />
Check your plants after summering them outdoors<br />
Before bringing your plants indoors again, check the leaves, under the leaves, around flower spikes, behind<br />
flowers and just under the rim of the pot for any sign of pests.<br />
Chewed up leaves are a sure sign of damage from slugs or snails.<br />
If you have summered your plants outdoors, even if you do not see any sign of insects you should consider treating<br />
them against insects before bringing them in.<br />
Check your plants periodically<br />
It is a good idea <strong>to</strong> check your plants periodically for any sign of insects. It is much easier <strong>to</strong> eliminate insects<br />
before they severally infest your plants.<br />
8.2 Pests that may affect your <strong>orchid</strong>s<br />
Scale<br />
The two most common scales that may affect your <strong>orchid</strong>s are the soft scale and the armored scale.<br />
Soft scale may hide in dried sheaths at the base of pseudobulbs of Cattleyas or similar plants. Remove the dried up<br />
sheaths <strong>to</strong> eliminate hiding places for them. Remove as many of the scale as you can see, then treat with an insecticide.<br />
Hard scale looks like tiny turtles. They will usually be under the leaves of Phalaenopsis or Cattleyas, sometimes<br />
hiding in the pot. Remove as many as you can see, then treat with an insecticide.<br />
Mealybugs<br />
They are white and look sort of cot<strong>to</strong>ny, may be 1/4” in size. They can be on or under the leaves, on flower<br />
stems, on buds, behind flowers, in the pot,.... Remove as many as you can see, then treat with an insecticide.<br />
Removing as many of the above insects as you can.<br />
For all of the above use a soft <strong>to</strong>othbrush or cot<strong>to</strong>n swabs <strong>to</strong> remove as many of the insects as you can. Dip your<br />
<strong>to</strong>othbrush / your cot<strong>to</strong>n swabs in alcohol before using them <strong>to</strong> remove the insects.<br />
Aphids<br />
The mots persistent of them, as they reproduce on a short, 3 day cycle. Usually found on new growth, new<br />
leaves, on flower stems and flower buds, they suck the juices out of the plants and can cause substantial damage<br />
and leave marks on the leaves. Because they fly it is difficult <strong>to</strong> remove them individually. In warm sunny<br />
weather take the plant outside and use a garden hose <strong>to</strong> shake them off the plant. Then treat with an insecticide.<br />
Fungus gnats<br />
Look like small black flies. Are mostly hiding in the pot and fly our when you water. They are attracted by potting<br />
material that stays damp and by decaying plant material (dead roots, leaves,...). They feed mostly on dead<br />
plant material but they may attack roots, especially those of Cymbidiums. Because they hide in the pot you can<br />
not remove any. You have <strong>to</strong> treat them by immersing the pot in an insecticide solution.
Spider mite<br />
Are very small and can not be seen individually without a magnifying lens. You can detect them by looking<br />
under the leaves for tiny silvery pits where they have sucked the plant juices. Another way <strong>to</strong> see if they are any<br />
is <strong>to</strong> place a white paper <strong>to</strong>wel under the leaf and rub the leaf <strong>to</strong> make them fall on the paper <strong>to</strong>wel. Spider mites<br />
will thrive in dry (<strong>to</strong>o low humidity) environments. The best defense is maintaining reasonable humidity, but if<br />
you have spider mites you’ll have <strong>to</strong> treat them with an insecticide / miticide. For best results immerse the pot in<br />
an insecticide / miticide solution.<br />
Thrips<br />
They do not occur frequently, but if they do, you’ll notice it because of deformed or spotted flowers. They are<br />
difficult <strong>to</strong> eradicate because they tend <strong>to</strong> lodge in the flower buds and under sheaths where they are protected<br />
from insecticide sprays.<br />
8.3 Treating insects with an insecticide.<br />
Caution - Warning<br />
If you are going <strong>to</strong> use commercially available pesticides please always follow the directions on the label.<br />
Some of these insecticides are very potent and you should make sure <strong>to</strong> apply all required precautions against<br />
poisoning yourself, others around you or your pets.<br />
You can prepare a safe, effective insecticidal soap by mixing 1 teaspoon of a mild liquid dishwashing detergent<br />
(the 409 cleaner, regular, works very well) <strong>to</strong> a quart of lukewarm water.<br />
How insecticides work<br />
Systematic insecticides are <strong>to</strong> some degree absorbed by the plant and may offer residual protection for a few<br />
weeks. Systematic insecticides tend <strong>to</strong> be more dangerous than other insecticides.<br />
Many insecticides kill only the adult insects, not necessarily the eggs or the larvae (immature insects).<br />
Insects develop resistance <strong>to</strong> insecticides. What this means is that some of them are not affected by the insecticide<br />
and these will reproduce. Treating these with the same insecticide will not kill them.<br />
To avoid resistance you should consider rotating insecticides, that is you make the first application with one<br />
insecticide, the second application with another and the third one either with the first insecticide or with a third<br />
one. Rotating is not necessary with the insecticidal soap you prepare because this insecticidal soap works by<br />
suffocating the insects.<br />
Treating for a limited infestation<br />
If the infestation is not excessive, spray thoroughly the new growths, leaves (both sides), flower stem, back of<br />
buds and flowers with the insecticidal solution.<br />
Treating severe infestations<br />
If the infestation is widespread dip the hole plant for 15 minutes of so in the insecticide solution.<br />
8.4 Making sure the treatment is effective<br />
For the treatment <strong>to</strong> be effective you have <strong>to</strong> treat the plant (spraying or immersing) 3 times, at intervals of one<br />
week (intervals of 3 - 4 days for aphids).<br />
The reason you need <strong>to</strong> make more than one application is because the insecticide will kill the adults and a few<br />
days later the eggs will hatch and the cycle restarts unless you treat again <strong>to</strong> kill the hatches. Most of the time<br />
three applications one week apart (3 - 4 days apart for aphids) will eliminate the insect population.<br />
Caution !<br />
If you are going <strong>to</strong> immerse plants in a solution :<br />
• do it only on sunny days; if the weather is cool, cloudy or rainy, you’ll be much better off waiting a day or two<br />
before treating your plant(s),<br />
• do it early in the day; this will allow any water that got in between leaves or new growth <strong>to</strong> evaporate before<br />
nightfall,<br />
• do it with room temperature or lukewarm water as a difference of 10 degrees or more between the temperature<br />
of the water and the room temperature may cause injuries <strong>to</strong> the plants.
Slugs<br />
These are <strong>to</strong>ugh <strong>to</strong> treat as they emerge at night. In the old days the products <strong>to</strong> treat them were base on<br />
formaldehyde, a noxious product. Today you can treat them with a very effective and safe product called<br />
sloggo, available either in granular or liquid form.<br />
The product is available from Monteray Lawn & Garden Products, Fresno, CA (www.<br />
montereylawngarden.com; Tel. 559-499-2100).<br />
8.5 Diseases<br />
Viruses<br />
Occasionally you may come across a plant that has a virus. This may manifest itself by concentric or elongated<br />
black or brown or discolored circles on the leaves or black streaks on flowers and leaves. These will be repeated<br />
on all leaves / flowers. New leaves / flowers will at first appear free of it but as they age the virus will manifest<br />
itself. Unfortunately there is nothing you can do but discard the plant.<br />
Bacterial and fungal diseases<br />
These will appear if water stays in between leaves or if the potting material stays soggy, especially when the<br />
night temperatures are cooler (fall, winter, spring).<br />
You can treat these with fungicides like RD 20 or Physan 27, but the best way is <strong>to</strong> avoid these problems by<br />
practicing proper culture.
9 Cultural problems<br />
9.1 Cultural problems common <strong>to</strong> most <strong>orchid</strong>s<br />
9.1.1 Leaves<br />
9.1.2 Leaves or new growth<br />
9.1.3 Buds, flowers & flower spikes<br />
9.1.4 Roots<br />
9.2 Cultural problems-Phalaenopsis<br />
9.2.1 Leaves<br />
9.2.2 Flower spikes, buds & flowers<br />
9.3 Cultural problems-Cattleyas<br />
9.3.1 New growth & leaves<br />
9.3.2 Flower sheath, buds & flowers<br />
9.4 Cultural problems-Cymbidiums<br />
9.4.1 New growth & leaves<br />
9.4.2 Flower spike, buds & flowers<br />
9.5 Oncidiums and intergenerics with Oncidiums<br />
9.5.1 New growth, leaves<br />
9.5.2 Flower spike, buds & flowers<br />
9.6 Cultural problems-Paphiopedilums<br />
9.6.1 New growth, leaves<br />
9.1 Cultural problems common <strong>to</strong> most <strong>orchid</strong>s<br />
9.1.1 Leaves<br />
Leaves are dark green, look very healthy, but plant does not bloom:<br />
Probably due <strong>to</strong> insufficient light. Check your light level, move the <strong>to</strong> within one <strong>to</strong> one and a half feet of a<br />
bright, unobstructed windowsill (window exposure depends on type of <strong>orchid</strong>).<br />
Leaves are not as lustrous, eventually they shrivel:<br />
plant is not absorbing enough water. Check the root system. If roots are abundant, look healthy, are firm and are<br />
white, then the plant is being underwatered. If the root system does not appear healthy repot as soon as possible.<br />
Yellowing of leaves = chlorosis.<br />
May be due <strong>to</strong> excessive light and/or deficiency in nitrogen.<br />
Clear or watery spots on leaves:<br />
usually result from bacterial infection. Repot plant, treat plant with a fungicide, keep it on the dry side for a few<br />
weeks.<br />
Discolored area on <strong>to</strong>p of curled leaves or on leaf area exposed <strong>to</strong> light:<br />
most probably due <strong>to</strong> sunburn or excessive light for this type of <strong>orchid</strong>.<br />
Pitting on new foliage:<br />
tissue collapse due <strong>to</strong> use of <strong>to</strong>o cold water or because of <strong>to</strong>o cold temperatures.<br />
Tips of leaves are burned (black), roots are withered:<br />
plant is overfertilized or burned by fertilizer. Check your fertilizer dosage, make sure you water thoroughly with<br />
plain water once a month, make sure you do not water with fertilizer when the plant is completely dried out.<br />
Leaves turn yellow, then brown and die:<br />
probably due <strong>to</strong> fungi, as a result of excessive watering/soggy or decaying potting mix and/or excessive humidity<br />
possibly combined with <strong>to</strong>o cool temperatures. Unpot the plant, treat it with a fungicide, cut dead / brown<br />
growth and leaves, repot in fresh potting mix. Allow the plant <strong>to</strong> dry in between waterings.
Black streaks on leaves :<br />
may be caused by a number of cultural problems or by a virus. If due <strong>to</strong> a virus, this will eventually show up on<br />
all growths. Newly developed growth may at first appear normal, but eventually they will display same symp<strong>to</strong>ms.<br />
If this a plant you particularly like, you may have it tested for virus. Plants can not be cured from<br />
viruses, and viruses may be transmitted <strong>to</strong> your other plants through insects, water splashing from plant <strong>to</strong> plant,<br />
or from grooming without sterilizing instruments. If the plant has a virus, it’s best <strong>to</strong> dispose of it.<br />
9.1.2 Leaves or new growth<br />
Soft, rapid growth:<br />
may be due <strong>to</strong> excessive nitrogen<br />
New growths are smaller, not as plump than previous ones, are stunted, do not grow upright:<br />
the plant is under stress, either because of weakened root system or<br />
insufficient light or <strong>to</strong>o extreme temperatures, deficiency in nitrogen, or a combination of these. Check light,<br />
temperature levels & fertilizer dosage. Repot if needed.<br />
9.1.3 Buds, flowers & flower spikes<br />
Buds yellow and drop:<br />
extreme temperatures, extreme or insufficient light, drafts, <strong>to</strong>o dry air, inadequate watering, micronutrients deficiency<br />
or excesses or weak root system.<br />
Flowers do not open up fully:<br />
may be due <strong>to</strong> genetics, or by <strong>to</strong>o low temperatures, or may be due <strong>to</strong> <strong>to</strong>o low humidity or thrip damage.<br />
Flowers are <strong>to</strong>o small, colors are not as strong as before:<br />
most probably due <strong>to</strong> insufficient light, and or <strong>to</strong>o extreme temperatures.<br />
Flowers fade <strong>to</strong>o fast:<br />
may be caused by <strong>to</strong>o high or <strong>to</strong>o low temperatures, exposure <strong>to</strong> direct sunlight, exposure <strong>to</strong> drafts, <strong>to</strong>o low<br />
humidity, fertilizing or micronutrients deficiency, inadequate watering or poor condition of the root system.<br />
Too few flowers:<br />
weak plant, <strong>to</strong>o low light, phosphorous deficiency.<br />
Brown streaks or mosaic patterns on flowers:<br />
may be due <strong>to</strong> a virus.<br />
Poor display of flowers:<br />
When buds start <strong>to</strong> form on the flower spikes, be careful not <strong>to</strong> change the orientation of the flower spike (which<br />
leans <strong>to</strong>ward the source of light) so as <strong>to</strong> get the best possible display of flowers.<br />
9.1.4 Roots<br />
Are black or brown:<br />
may be damaged (broken) or have rotted (root rot fungus). Cut damaged & rotten roots. If rotted, treat with a<br />
fungicide, repot plant, keep a little drier.<br />
Chewed or missing tips:<br />
chewed by pests (millipedes, sowbugs, snails or slugs).<br />
Dead tips:<br />
may be caused by salt built-up due <strong>to</strong> <strong>to</strong>o hard water or excess fertilizer or not leaching medium regularly.<br />
Deformed:<br />
may be due <strong>to</strong> chlorine deficiency.<br />
Stunted roots:<br />
probably because of micronutrients deficiency.
9.2 Cultural problems-Phalaenopsis<br />
9.2.1 Leaves<br />
New leaves are smaller than previous ones: the plant is under stress, either because of weakened root system or<br />
insufficient light or <strong>to</strong>o extreme temperatures or a combination of these. Check light and temperature levels.<br />
Repot the plant if needed.<br />
Crinkled leaves: may be due <strong>to</strong> insufficient watering.<br />
Limp, dull, eventually wrinkled leaves: the plant is not absorbing enough water, either because of a poor root<br />
system or because of inadequate watering. Check root system, repot, water as required.<br />
Reddish leaves: is often normal on the underside of leaves. On the upper side it may be due <strong>to</strong> excessive light, or<br />
deficiency in nitrogen and/or deficiency in phosphorous.<br />
Red coloration on new foliage: may indicate a fungus. Treat with a fungicide.<br />
Reddish or discolored bot<strong>to</strong>m leaves: bot<strong>to</strong>m leaves are dying back. May be normal when new leaves are<br />
formed. Mature plants carry from 4 <strong>to</strong> 6 leaves, and replace 1 or 2 per year. May be also a result of repotting<br />
shock, especially if newly repotted plants are not misted and if they are subject <strong>to</strong> <strong>to</strong>o high light.<br />
No or limited new leaves: often result from nitrogen and/or phosphorous deficiency.<br />
Leaf loss: if it is not due <strong>to</strong> aging while new leaves are being produced, is an indication of stress which may<br />
result from extremes in temperatures, humidity, watering or phosphorous deficiency. Treat plant with a fungicide/germicide,<br />
repot in sphagnum moss, keep at very high humidity (enclose in plastic bag?). This will probably<br />
not revive the plant but is may induce it <strong>to</strong> produce keikis.<br />
9.2.2 Flower spike, buds, flowers<br />
Flower spike is crooked or discolored:<br />
may be due <strong>to</strong> a virus. Isolate plants until final diagnosis.<br />
Limp spikes:<br />
may be normal for some species and resulting hybrids, otherwise indicates <strong>to</strong>o low light.<br />
Too short flower spikes:<br />
usually due <strong>to</strong> excessive light.<br />
Spikes turn brown at the tip:<br />
were subjected <strong>to</strong> <strong>to</strong>o cold water, resulting in collapsing tissue.<br />
Spike develops keikis:<br />
normal for some species, but can be cause by <strong>to</strong>o high temperatures, insufficient light, decaying potting<br />
medium, plant in poor health.<br />
Thin flower spikes:<br />
may be due <strong>to</strong> phosphorous deficiency or <strong>to</strong>o low light.<br />
Flowers rot or are spotted:<br />
caused by fungi if water is allowed <strong>to</strong> stagnate on them or because of excessive moisture/humidity.<br />
You can help the plant by cutting the flower stem after flowers have faded. Removing the spike after flowers<br />
have faded will induce plant <strong>to</strong> generate more and larger flowers at its next blooming season.<br />
Plants getting right conditions will spike more or less naturally in late fall or winter or early spring. You can<br />
induce flowering by subjecting plants <strong>to</strong> 2 or 3 weeks of night temperatures in the mid <strong>to</strong> low 60’s. Flower spikes<br />
should appear about six weeks later.
9.3 Cultural problems - Cattleyas<br />
9.3.1 New growth & leaves<br />
Growth turns brown, then dies:<br />
probably due <strong>to</strong> fungi, as a result of excessive watering/soggy or decaying potting mix and/or excessive humidity<br />
possibly combined with <strong>to</strong>o cool temperatures. Unpot the plant, treat it with a fungicide, cut dead / brown<br />
growth and leaves, repot in fresh potting mix. Allow the plant <strong>to</strong> dry in between waterings.<br />
No or limited new growth:<br />
may result from nitrogen and/or phosphorous deficiency, or damage / rotting of growth buds (at basis of previous<br />
growth).<br />
9.3.2 Flower sheath, buds & flowers<br />
Sheath dries out:<br />
may be because plant was immature (1st attempt at blooming) or may be species related as some Cattleyas will<br />
bloom after the sheath has dried out.<br />
Sheath and/or buds turns brown and are watery:<br />
water stagnated in/on the sheath and provoked sheath and probably buds) <strong>to</strong> rot. Gently open sheath <strong>to</strong> check if<br />
buds are still green. If yes, completely open sheath <strong>to</strong> expose buds . If buds are yellow or brown, remove sheath<br />
& buds. In either case make sure water does not gather and stagnate there.<br />
9.4 Cultural problems - Cymbidiums<br />
9.4.1 New growth, leaves<br />
New growths are smaller, not as plump than previous ones, are stunted, do not grow upright: the plant is<br />
under stress, either because of weakened root system or insufficient light or <strong>to</strong>o extreme temperatures,<br />
deficiency in nitrogen, or a combination of these. Repot the plant, check light, temperature levels, fertilizer<br />
dosage,....<br />
Leaves turn yellow and die:<br />
probably due <strong>to</strong> insufficient watering<br />
Growth turns brown, then dies:<br />
probably due <strong>to</strong> fungi, as a result of excessive watering/soggy or decaying potting mix and/or excessive humidity<br />
possibly combined with <strong>to</strong>o cool temperatures. Unpot the plant, treat it with a fungicide, cut dead / brown<br />
growth and leaves, repot in fresh potting mix. Allow the plant <strong>to</strong> dry in between waterings.<br />
No or limited new growth:<br />
may result from nitrogen and/or phosphorous deficiency, or damage / rotting of growth buds (at basis of previous<br />
growth), or poor root system, but often due <strong>to</strong> poor repotting or overdue repotting.<br />
9.4.2 - Flower sheath, buds & flowers<br />
Sheath and/or buds turns brown and are watery:<br />
water stagnated in/on the sheath and provoked sheath and probably buds) <strong>to</strong> rot. Gently open sheath <strong>to</strong> check if<br />
buds are still green. If yes, completely open sheath <strong>to</strong> expose buds . If buds are yellow or brown, remove sheath<br />
& buds. In either case make sure water does not gather and stagnate there.<br />
Buds dry and drop:<br />
Bud drop may occur if day or night temperatures are <strong>to</strong>o high. Ideally when buds start <strong>to</strong> develop (usually in<br />
fall or winter), day temperature should not go much above 65 F and night temperatures should, if possible, be<br />
maintained between 50 F and 60 F.<br />
Flowers yellow and drop:<br />
extreme temperatures, extreme or insufficient light, drafts, <strong>to</strong>o dry air, inadequate watering, micronutrients deficiency<br />
or excesses.
9.5 Oncidiums and intergenerics with Oncidiums<br />
9.5.1 New growth, leaves<br />
New growths are smaller, not as plump than previous ones, are stunted, do not grow upright:<br />
the plant is under stress, either because of weakened root system or insufficient light or <strong>to</strong>o extreme<br />
temperatures, deficiency in nitrogen, or new growth growing over the edge of the pot, or new growth <strong>to</strong>o high<br />
up (and roots not taking hold in the medium), or a combination of these. Repot the plant, check light, temperature<br />
levels, fertilizer dosage,....<br />
Leaves turn yellow, then brown and die:<br />
probably due <strong>to</strong> fungi, as a result of excessive watering/soggy or decaying potting mix and/or excessive humidity<br />
possibly combined with <strong>to</strong>o cool temperatures. Unpot the plant, treat it with a fungicide, cut dead / brown<br />
growth and leaves, repot in fresh potting mix. Allow the plant <strong>to</strong> dry in between waterings.<br />
Growth turns brown:<br />
same as above.<br />
No or limited new growth:<br />
may result from nitrogen and/or phosphorous deficiency, or damage / rotting of growth buds (at basis of previous<br />
growth).<br />
9.5.2 Flower stem, buds & flowers<br />
Flower stem dries out and does not develop:<br />
probably due <strong>to</strong> insect damage, plant not absorbing enough water or temperatures out of range (i.e. <strong>to</strong>o low day<br />
time, <strong>to</strong>o high night time).<br />
Flower stem turns brown and is watery:<br />
water stagnated in/on the flower stem and provoked flower stem and probably buds) <strong>to</strong> rot. Remove flower<br />
stem, make sure water does not gather and stagnate there.<br />
9.6 Cultural problems - Paphiopedilums<br />
9.6.1 New growth, leaves<br />
New growths are smaller, are stunted, do not grow upright:<br />
the plant is under stress, either because of weakened root system or insufficient light or <strong>to</strong>o extreme temperatures,<br />
deficiency in nitrogen, or a combination of these. Repot the plant, check light, temperature levels, fertilizer dosage,....<br />
Leggy plants growing tall:<br />
may indicate plants are not receiving sufficient light (they are stretching themselves <strong>to</strong> reach the light).<br />
Tips of leaves are brown or spotted:<br />
plant is not absorbing enough water either because of insufficient watering or because of root rot.<br />
Leaves turn yellow, then brown and die:<br />
probably due <strong>to</strong> fungi, as a result of excessive watering/soggy or decaying potting mix and/or excessive humidity<br />
possibly combined with <strong>to</strong>o cool temperatures. Unpot the plant, treat it with a fungicide, cut dead / brown<br />
growth and leaves, repot in fresh potting mix. Allow the plant <strong>to</strong> dry in between watering.<br />
Watery spots on leaves that turn brown or gray or black, sometimes with yellow on the margins:<br />
usually result from bacterial infection. Repot plant, treat plant with a fungicide, keep it on the dry side for a few weeks.<br />
White spots and/or irregular dark patches:<br />
may also result from bacterial infection. Treat as above.<br />
No or limited new growth:<br />
may result from nitrogen and/or phosphorous deficiency, or damage / rotting of growth buds (at basis of previous<br />
growth), or setback if the plant was divided and left with only one growth.<br />
Note: If plants or portions of plants are infected by bacteria, take immediate action as the infection can spread rapidly<br />
and kill the plant. Unpot the plant, remove all affected area, treat with a fungicide/bactericide, repot in fresh media.