So then, even in mostly non organic mater, moss continues? Come to think of it, my fifth grade teacher told me that that the first plant that ever grew on dry grew on dry land, was moss on lava rocks (how did i remember that?).

just make sure you don't get this in your pot:
en.wikipedia.org/wiki/Polytrichum_commune

Dominion wrote: just make sure you don't get this in your pot:
en.wikipedia.org/wiki/Polytrichum_commune

any where around the yard, scary looking stuff