Question
QUESTION: Wayne,

What soil medium would you personally recommend for Phalaenopsis? Is there a particular mix of amendments that work ideally together??

Thank you,

Derick

ANSWER: There are commercially prepared orchid potting mixes that are available at most garden centers that provide orchid plants.  Among these are Lowes and Home Depot garden centers.  The best of these orchid potting mixes will contain fir bark, perlite and charcoal.  Usually they come in dry mixes for storage. You then select enough of this potting mix for repotting the plant(s) and soak it for a couple of hours prior to use.  Then, strain it to remove the dust size particles prior to use.

---------- FOLLOW-UP ----------

QUESTION: Wayne,

I like to blend my own soil mixes...do you think 1 part orchid bark, 1 part perlite, and 1 part charcoal would be a good soil medium for Phalaenopsis?

Thank you,

Derick

Answer
Derick, remember the growing conditions of your plant's ancestors.  Generally, they grow on tree limbs with their roots exposed to the air.  In this respect they differ radically from the usual houseplants. They need to have a fairly "open" potting mix and each ingredient in the mix serves a special purpose.  The fir bark provides support for the orchid roots, the charcoal helps to keep the potting mix open and is not subject to deterioration or decay, and the perlite helps to maintain humidity in the potting mix.  Remember that an "open" potting mix promotes the movement of air and water through the potting mix. Since fir bark will begin to turn to soil-like particles within a year, the finer, soil-like mixture holds more moisture and reduces air movement to the roots.  For this reason, and annual repotting in fresh orchid potting mix is advised.

Different growers have their own preferred formulation of ingredients.  I prefer about 5 parts of medium fir bark, to 2 part charcoal and one part perlite.  Remember that particle size of each of these ingredients is important. I prefer medium fir bark with the particle size 1/2-3/4 inch.  Charcoal particles should be about the same size as the fir bark.  For the perlite, I prefer the large perlite referred to as "sponge roc".  Each of these ingredients will contain a range of particle size and I screen out the really fine particles which can reduce air and water flow through the mix. Particle size that is too large will allow the potting mix to dry out more rapidly. Dry fir bark repels water and will draw water out of the roots so must be soaked to reduced the water repellancy prior to use.