Hi Ken, Thank you for your advice. I have some Jiffy mix on hand. I just tested the Jiffy mix after filtering out the vermiculite with a sieve. The fine peat moss that fell out of the sieve floats readily in water. I think I can work with it without a problem. It is going to take me awhile to get enough of them filtered, though. Well, I just have to start with a small batch : ) Thanks again, Tomoko