Is it good to cover the orchid pot surface with sphagnum moss? A detailed guide to using sphagnum moss

How do you use sphagnum moss to grow orchids? Is it good to cover the orchid pot surface with sphagnum moss

Some orchid growers say that spreading sphagnum moss on the pot surface retains moisture and gives a high germination rate; others say that sphagnum moss on the pot surface breeds bacteria and makes orchids prone to rot.

Many orchid growers in Chengdu spread sphagnum moss on the pot surface, and they do so even in summer, and the orchids still grow very well. I also spread sphagnum moss, though I have not noticed a high germination rate, perhaps because I grow them outdoors; nor have I found them prone to soft rot, possibly because the air permeability is good. I spread sphagnum moss because the growing medium is piled high and tends to fall out, so it serves to hold the medium in place.

But I have found that the biggest drawback of spreading sphagnum moss is that orchid roots tend to run along the pot surface. I see that sellers use plastic pots, where the humidity inside the pot may be high and this does not happen, whereas I prefer sand pots, where the medium below is not humid enough, so all the orchid roots tend to hug the sphagnum moss.

Another problem is that when grown outdoors, the sphagnum moss on the pot surface dries out very easily. When the sphagnum moss is dry, the medium below may still be moist; or when the sphagnum moss is dry and the medium below is also dry, then the medium becomes very hard to water thoroughly.