If emails and casual conversations are any indication, repotting is
traumatic for many orchid hobbyists. It is not surprising to most of us
that have been doing this awhile, because it was traumatic to us in the
beginning too. Given how different orchid roots look, the cost compared
to a petunia, and the number of pages in orchid books devoted to the
“dos and don’ts” of potting, fear is not surprising. So here is what
everyone should remember.
Getting two or more orchids from repotting one should never be the
reason to repot, although that is a frequent consequence. Repot when
your orchid is at risk because the potting media is breaking down or
there is some other problem, e.g. heavy scale infestation that cannot be
solved without removing the plant from its pot. Remember that the bigger
your orchid is, the more and larger flowers it will have. Always
sterilize any instrument that cuts an orchid. The best method is to hold
your snips in the flame for a few seconds making sure you have exposed
both sides of the entire cutting surface to the flame. A hot cutting
tool effectively sterilizes the cut surface of the plant.
Do not worry about damaging roots, since most will ultimately die from
the repotting anyway. Some expert growers remove almost all roots when
they repot to avoid them rotting later and infecting the rest of the
plant. If repotted at the correct time of the year, your orchid will
quickly re-grow roots, but it may take a few years to acquire the root
mass it had before repotting, hence the suggestion to avoid repotting
unless absolutely necessary.
Many times I sit a cattleya with all of its roots removed in the bottom
of a clay pot in a shaded portion of the greenhouse until I see tiny new
roots starting. Only then do I add the medium and complete repotting. On
occasion, I forget a plant and find it fully rooted to the pot the next
spring. Again, the key point is that one should only repot during the
growing season; i.e. now.
Most books recommend wetting the medium before using it, a
recommendation that I do not endorse. This is an open invitation for
bacteria and fungi to invade any open wounds on the plant. It is best to
use dry medium and wait at least several days before watering your newly
repotted orchid. Some growers lay their divisions on newspaper in an
unused bedroom until new roots appear. Why waist a pot and medium if the
division is not going to grow well.
The key to all repotting is to remember that your orchid has been
shocked and lost most of its ability to obtain water. Cattleyas,
dendrobiums and other orchids with thickened leaves will be fine if the
plant is shaded heavily after repotting until they get new roots. Then,
gradually give them more light. Other orchids that are terrestrial-like
and/or have fine roots or thin leaves, need more care and may require
some misting until new roots appear.
The one exception to the need to keep roots dry is when a medium is used
that is toxic to bacteria and fungi, e.g. sphagnum or osmunda. The pH is
so low that almost no bacteria harmful to plants will grow. This seems
to be the medium of choice for many phal growers.
