posieh, I just saw an episode about this very thing on the home and garden network.

They bought a tub of plain yogurt. Used a paintbrush and painted the yogurt on the outside of the clay pots. That was it!

Sue

I've heard that you can paint "buttermilk" onto the sides of terra cotta or concrete forms and then shake some moss over the piece. The moss spores stick to the wet buttermilk and viola, grows moss on your piece.

Sal

I heard it had to be the yogurt with live cultures, not sure though.

Thanks folks. I haven't had time to try it yet. But it seems like the live culture would make sense.But then, where do I find "live cultures"?

I know you can grow moss between flagstones by blending moss and buttermilk and pouring it between the stones. I dont think you would need to use live cultures. btw that is just regular old yogurt.