Cymbidium won’t grow

[Roberta]

Volcanic rock is fine. Maybe even better than perlite. Does the same thing. For time-release fertilizer, doesn't much matter... look for one that claims 6 months, ideally one with a bit of extra nitrogen (first number) . Osmocote, Nuricote, Dynamite are the ones I know. They leach more on temperature than water. So if you apply in the spring, as the weather warms they're give an extra boost. And be pretty much pooped out by fall, when you don't want to fertilize as much.
Losing a few roots is no big deal. Cyms are root machines when they are happy. When you repot, pack the new medium firmly. (They like "tight shoes") With bark + inorganic you can do that and still have good aeration. I would get rid of the outer decorative pot. I think that airflow will be better without.

[mook1178]

I have found the cymbidium mix from Repotme works great.

TBH, I cannot say enough about the mixes I get from repotme. African violets, orchids, succulents. THey are a little more expensive, but use top quality media to make their mixes and my plants explode with growth when repotted into their mixes. Only downside, is the need t fertilize more as their mixes are do not contain soil.

[Girl_With_An_Orchid]

mook1178, good to know. I’ve already repotted them but I’ll remember that for next year. Hopefully all these changes will make a difference! I’d love to see them bloom again one of these days!