Each year there are many email questions related to problems with growing specific orchids or asking for help diagnosing some disease or pest. There is also the occasional general question which asks “what is the most difficult challenge I face growing orchids?” It is also a question I get when I speak to orchid societies. The answer is growing many different species and hybrids, which come from many different habitats in one greenhouse.
Orchid species are always the most difficult because they evolved within
a specific habitat and environment and often there is some critical need
for rest, dryness, etc during some part of the year that must be met or
the orchid dies or does not flower. Some hybrids derived from these
species may also have a similar requirement, but typically hybrids are
more forgiving if one forgets to give them the appropriate conditions.
In many cases a dry period is required to coincide with drought in the
orchid’s native habitat. It is fairly easy to set plants requiring a dry
period aside and limit watering if there is lots of space or there are
just a few orchids, but more difficult if one has several thousand
orchids in a relatively small space. Over the years I have developed
several approaches that have allowed me to manage problematic orchids.
The primary approach has been to place plants that require dry
conditions in extremely coarse media or even to mount them. They are
grown in the brightest part of the greenhouse where they dry quickly
even when they are in a growth mode. While they may dry out more than
would be ideal during their growth cycle, they also are more than dry
enough during their dry season as well. For most, the dry requirement
coincides with winter when watering is reduced anyway. I also take
advantage of the change in the angle of the sun so that these orchids
get more direct light in winter.
More problematic are orchids that want more water in winter and less in
summer. These have not fared well over the years, but lately they have
been moved outside during summer where they get only the occasional
shower and little or no fertilizer and then moved under vandas in
baskets during winter as these get watered most during the cool part of
the year.
There are also orchids in my collection that do not like summer heat.
Some of these come from high elevations where nights regularly go down
into the 40’s F, but never above 80 F during the day. I grow these
mounted or in very coarse media also and keep them under benches in
summer where it is coolest. Admittedly, they do not thrive in summer,
but survive. Once the Fall Equinox arrives, they are moved into more
light and in winter they go right against the glass in places where
water drips during the coldest nights. Typically, they grow well and
flower before the heat returns and they are returned to their under
bench hiding spot where lots of air movement is maintained. If I forget
to move them under the bench in time they go downhill fast and have been
lost.
Roaches have been my biggest enemy since arriving in Florida. After the
last mention of this problem in the “Tips” column there were several
suggestions regarding Diatomacious Earth. I have used this before in the
house, but not sure if it would help in a greenhouse. Nevertheless, I
obtained a bag and spread it on tables, but not on plants. Within a week
or two dead roaches appeared on the greenhouse floor. These were the
larval stages that cannot fly, but this is the first time I have had any
success again these vermin. Thanks to those who sent me the suggestion.