In defense of Sphagnum moss for Cattleya
 

Just wanted to share a bit about using sphagnum for Cattleya and the results I’ve encountered. Maybe 3-4 years ago I began moving all my Cattleya to sphagnum moss. At first I was prepared for the worst seeing as my plants are all in South Florida, minutes away from the Redland festival grounds. The plants were gradually moved into tall clay pots with moss and a layer of packing peanuts.

This is the first year many of the seedlings are graduating from 4in pots up and I cannot understate my satisfaction with moss as a medium. The roots are insane on all of the plants I’ve reported this year. Bifoliates, unifoliates, species and hybrids. Not a single mushy root in sight, even from older back bulbs. Here is an example from this morning. The best part is with correct watering practice, the moss has retained its fluffiness and a quick pour through PH test shows no real souring of the media. Without disturbing the roots this will go into a larger pot, again with a layer of styrofoam peanuts and moss.

Yes, sphagnum works great for many people.

That’s great! Did you have to alter your watering frequency compared to bark?

There is no potting medium that is "better" or "worse" for any orchid. Why? Because potting medium is but a single variable out of many, and no single variable fully defines the "proper conditions for that particular plant".

Don't need to defend it...I believe it works in your conditions.

Sphag works well when it dries rather quickly, bringing new O2 to the rootzone. I doesn't work as well when the environment doesn't allow it to dry quickly, suffocating the roots.

I find sphag works wonderfully in a lower humidity, higher temp environment where drying occurs more rapidly.

I also think it works better in a lower light environment to minimize algae/moss growth on top, which can decrease evaporation

I put a Cattleya Hawaiian Prominence, 'America' in NZ sphagnum moss. I paired it with a clear pot that has plenty of holes for ventilation. It needed more consistent moisture so moss was a good option.

Some Cattleyas are recommended to be mounted or in baskets) so, in my conditions, I would not try to put those in moss. I have many plants and I tend to tailor the potting to the individual plant after research to discover what they prefer. Now that I have less orchids, I have been doing that with them lately, too.