I use a mixture of coir, soil and charcoal in my terrarium with a top 1" layer of coir. The substrate is loosely packed for good drainage.

Why does my pillow moss always yellow and die on me? It's in a sunny, but not too sunny, location.

Thanks!
James

If you want a fairly good terrarium moss, try java moss. it thrives in moist to wet conditions. some selaginella, although not true mosses, do very well in terrariums. sphagnum moss may spring back to life in wet conditions but soon dies, as it is a temperate moss.

you could also try some moss-like plants such as babys tears. however, it will soon become a weed, so prune it regulary if it becomes a pest.

~chris