If Linda's sand is what we get from the bottom of a bin of red cinder mulch here in Oregon, a rock gardening acquaintance swears by it as an amendment to soils for alpines. He's a plant scientist and says it contains some particularly good nutrients. I agree with Bob that it should not have too many fines, but the bin scrapings my friend uses are not graded. I myself use a lot of white pumice, and I prefer the unwashed product because here too the fines have nutritional value. Jane McGary, Portland, Oregon, USA On 2/5/2021 1:14 AM, Linda Press Wulf via pbs wrote: > I’ve ended up with three large bags of red volcanic sand. > > Would it be good to add it (and how sparingly?) to my bulb potting mix of volcanic pumice and coir? How about spreading a half-inch all over my large bed of South African plants to lighten the clay soil? And if so, can I wait for it to integrate into the soil ( like a side dressing of compost) without my digging it into the soil? > > I live in the Berkeley hills, Northern California, and the bed is on a sunny slope. I spray water about once a fortnight in the dry summer. > > I would appreciate any advice. > Linda Press Wulf > _______________________________________________ pbs mailing list pbs@lists.pacificbulbsociety.net http://lists.pacificbulbsociety.net/cgi-bin/… Unsubscribe: <mailto:pbs-unsubscribe@lists.pacificbulbsociety.net>