Rockwool - Coelogyne cristata
 

I purchased this species last summer, and it has grown very quickly. It has more than doubled in size, and the more than half of the plant is hanging over the edge of the 4 inch pot that it came in. It is still growing in the original sphagnum moss. I've read that Coelogynes can sulk after being repotted, so in order to minimize the frequency of repotting, I'd like to pot it in an inorganic medium that will hold sufficient moisture, namely rockwool. Does anyone have experience growing Coelogynes or similar orchids in this medium?

Before choosing rockwool as a growing medium, you might want to research possible health hazards associated with rockwool.

I grow my C. Cristata in a large (30 cm) net pot that is lined with sphagnum moss. The interior space is a mix of medium bark, charcoal and sphagnum. My plant has become pretty huge, growing from a 10 cm pot to overflowing the edges of the large pot in just 4 years. Each year I get a lot of growth as long as I provide ample water, adequate fertilizer and Cattleya-level light.

OW, how often do you repot your plant? Does it "sulk" for a period of time afterward? Are these health hazards human or for orchids?

nope

The health hazards are for humans - just Google it and come to your own decisions.

For my C. Cristata, I potted it once, four years ago, as described, it has been happy ever since.