Watch the timelapse video! www.youtube.com/watch?v=uqpWIbLoAd0
I just recently did an experiment trying to make "moss paint" I've blended up a concoction hoping moss will grow from it. I went back to check on it after a few days. It's still there, just no moss growing. This one isn't the greatest spot, as it probably gets too much sun light, but I've got a few other places that might be better. I hope this works!
On a side note, check out the asperatus clouds in the last clip of the timelapse video I linked. I've see them before, I've also seen a handful of photos that are much more dramatic than these ones, but I've never seen them in motion. Quite the sight to see.