Gastil wrote >Having heard good things about pumice on this list, >I went to our OSH and purchased a small bag of Black Gold brand pumice. >It was about 10 times heavier than I expected pumice to be, but they >assured me that was just because it was wet. >At home, I noticed it had a lot of dust, which I did not think I >wanted in my growing medium >(not having read the note from Jane yet about the dust containing >useful minerals). >When I washed the pumice, I noticed it sank. I expected pumice to float. If the Oregon white pumice is bagged during damp weather, it will be wet. When I buy bags of it (4 cubic feet per bag, which is a BIG bag) in winter, the bag weighs 80 to 90 pounds; in summer it weighs about 60 pounds. (Must remember to stock up in August!) And yes, it will sink, even when it's dry. You can buy both washed and unwashed pumice here. I prefer the unwashed product because of the available nutrients in the fines. This pumice also raises the pH of a mostly acidic soil mix slightly. A geologist friend of mine once told me that mixing peat with pumice will eventually cause the pumice to break down because of a chemical reaction. I have not noticed this, but I don't usually keep the seed mix (the only one with peat) more than three years. I would never put vermiculite in planting soil, but I have used it to root cuttings and it's also excellent for packing bulbs for shipping, especially if they have to be kept very slightly moist. It perhaps should be mentioned that many of the ingredients being discussed in this thread need to be handled with care not to breathe in much of the dust. I worry sometimes about developing silicosis from using so much sand, but a recent chest x-ray (for bronchitis) gave me the "all clear." Vermiculite is said to be hazardous in this respect. Milled sphagnum moss (not the same as sphagnum peat) has been implicated in transmitting a pathogen, but I don't recall the details; I use the former occasionally when growing plants from seed that are very prone to damping off. Like Peter Taggart, I used to use forest humus as the organic component of my bulb soil -- when I had a forest. (Still have it, please buy it!) I never bothered to sterilize it, though I did sieve it and pick out the visible bugs. My feeling is that if you're growing your container plants outdoors, especially in the country, there isn't much point in sterilizing the soil. Soils for seeds should be more sterile, and for cuttings, even more. Jane McGary Portland, Oregon, USA