Hello Bob, > I used gray lava rock in pots of moraeas one year and the did terrible > compared to non lava. What about granite instead. Where can it be easily > obtained. The problem is local rock and minerals are cheap and available and not many people ship heavy and cheap products like rock or kitty litter long distances. I don't think there's much granite anywhere near coastal Northern California. There is a lot in the Sierras. If you could put a shovel and a few 5-gallon buckets into your trunk and then dig up a few buckets from some of the streams flowing down from the Sierras to the Central Valley that would be mostly granite. Of course, it's probably illegal plundering of California's natural resources. Leo Martin Phoenix Arizona USA