Cutting back old Phalaenopsis orchids

[Lorne Stobbs]

I have a number of large Phalaenopsis orchids with an abundance of aerial roots rising up the stem about 6" above the pot. I would like to unpot the plants, wash free the potting medium, and excise the lower mass of roots leaving only the upper aerial roots. I was thinking of drying the cut stem end, putting some fungicide or cinnamon on it, and then repotting the plant. Is this feasible? The plants have become too large and unmanageable for the space I have available.

[DirtyCoconuts]

If the lower roots are healthy it could hurt the plant. Can you post a pic?

Would repotting it all into a larger pot not work?

[JScott]

I've done this with Phals that lose their lower leaves as they get old, leaving an unsightly bare stem. What you are suggesting is perfectly fine, as long as the top part of the plant has plenty of roots. When I pot the top part of the plant, I put any roots that can easily be coaxed into the pot without breaking into the pot, and the ones that won't fit in the pot, I just leave in the air. I suggest applying a dose of KelpMax to help get the new roots growing vigorously.

If the lower part of the plant still has some good roots, you will probably get a side shoot growing from the stump, and you'll end up with a second plant. You may want to leave the upper portion of the plant sitting out for the wound to dry over for a day or two, and like you said, dusting with cinnamon or fungicide is a good practice.