Most
repotting should be complete by now except for plants that have special
requirements. Repotting is a
great time to assess how well your orchids have grown by simply examining
roots, old media, and the size of the plant.
If all of your repotted orchids are requiring larger pots then
last year’s, then media, fertilizing, watering, etc have been successful. If repotted orchids had few roots and smaller
leaves it may be necessary to change one or more of your cultural practices.
If you keep records of what you do each month, e.g. what fertilizer
was used or how frequently plants were watered, the task of assessing
what went wrong will be easier.
Orchid culture involves many facets
from light to water. Changing
any one variable requires that others be altered as well. More light usually requires more frequent watering,
while conversion to plastic pots from clay may require less. New media may require more or less fertilizer.
Most cultural problems revolve around water; too much, too little,
or water of poor quality. Orchids need better water quality than do humans.
People have various organs to rid their bodies of unwanted salts,
but plants must live with what you provide.
That is why water free of salt (dissolved stuff) is so important.
Ideally, the only salts you want in the water you give your plants
are those needed for growth, which are macronutrients (N, P, K) and
micronutrients (about 30 other elements needed in tiny quantities). Unless you use Reverse Osmosis or deionized water most micronutrients
are already there. Fertilizers
recommended for orchids supply the macronutrients.
If a problem was noted with your
culture the solution typically involves water.
If you cannot stop over watering, switch to a media that is more
porous or one that degrades more slowly.
Clay pots dry faster than plastic and offer another solution. If you often forget to water consider the opposite
or growing orchids tolerant of drought. Paphs and Phals do not like their roots to totally dry out, while
many groups with pseudobulbs require drying.
Some of this is learned by “trial and error” or “survival
of the fittest”. If Paphs
grow well for you, but Cattleyas grow well for a year or two then stop
blooming you can conclude that the needs of the low light, water-loving
Paphs are being met, but the higher light Cattleyas are not.
Growing Orchids begins with advice from books or friends, but
ultimately is trial and error learning tempered by availability of water,
media and other supplies.
The past year’s repotting
has revealed some strikingly successful experiments in my greenhouse
with both time-released fertilizers and with coconut chips. Both had been tried before, but were not successful under my cultural
conditions. One well-known Paph
grower recently published an article noting successful use of coconut
chips added to Paph mixes in place of fir bark. Several area Phal growers had added coconut chips to their mixes
years ago with mixed results. The
addition of coconut chips to the traditionally heavy Paph mixes seemed
to prevent the compaction of the mix and the required repotting. The secret was in removing salt from the coconut
chips before using them by repeated soaking. My first batch of coconut chips required several weeks of soaking
to decrease the salt content from over 10,000 to less than 20 ppm. Using the coconut chips right out of the box
would have meant disaster. I
already did that once. The salt
purged chips did just what was suggested in the article and Paphs grown
in the mix with coconut chips had far better roots and better yet, did
not require repotting after 6-8 months.
An experiment using coconut chips
in Cattleya mixes, while not complete, found one problem, mold. There is a common white-colored mold that occurs
in fir bark that makes the bark water repellent. This appeared in mixes with coconut bark.
The addition of small amounts of redwood bark should eliminate
mold as it does with fir bark. Next year’s repotting will reveal if this
works or not.
Another success was the near elimination
of small flies whose maggot larvae live in the media. While not a real problem, these flies can be
a nuisance and accelerate media breakdown.
A few small butterworts (carnivorous plants) was all that was
required. I do not have a commercial
source for butterworts, but Carter & Holmes has a species of sundew,
another carnivorous plant, which should also work well in greenhouses. Carnivorous plants are excellent indicators
of water quality as well and will die quickly if water quality is poor.
The last successful experiment
is one that seems too good to be true.
Slow release fertilizers such as Osmacoat have been around for
years, but tend to release too much fertilizer at once damaging roots. A new product, Nutricoat, has proven remarkable
because it did no damage to roots or even leaves when accidentally left
on them. Best yet, Cattleyas
grew faster, bloomed better, and still had the thick hard leaves desired. This product is not available in small quantities
locally, but has been repackaged into smaller quantities and is available
at Carter & Holmes for the hobbyist. For growers with just a few plants and that do not want to spend
time mixing fertilizers, this is the product for you. It lasts a long time and is still working over a year after it was
first applied. My experiment
involved Cattleyas Nutricoat
has not been used on other genera, at least in my greenhouse, so be
cautious if you use this on other genera in more dense media.