Thanks for the tips and your best wishes, Fred.
After some consideration, I think that I am going to use a combination of a planting mix that I use in my vegetable beds (most of the native soil in my garden is acidic clay), along with small-sized redwood mulch and some vermiculite. I guess I will have to add lime to get the pH right, and will then amend with alfalfa pellets and time release fertilizer.
