When cooler, or under dull conditions, fertilizer should be applied once a month. Potting Potting is best done in the spring, after blooming. Phalaenopsis plants must be potted in a well-draining mix, such as fir bark, tree fern, various types of stone, sphagnum moss, or combinations of these. Potting is usually done every 1-3 years. Mature plants can grow in the same pot until the potting medium starts to decompose, usually in two years.
Root rot occurs if plants are left in a soggy medium.
Seedlings usually grow fast enough to need repotting yearly, and should be repotted in a fine-grade medium. Mature plants are potted in medium-grade medium. When mature, a plant may stay in the same pot size for many years, but must have the medium changed. To repot, remove all the old medium from the roots, trim soft, rotted roots, and spread the remaining roots over a handful of medium in the bottom of a new pot. Fill the rest of the pot with medium, working it through the roots, so that the junction of the roots and the stem is at the top of the medium.