I posted something similar on an old thread, but then read that it is best f I start a new thread. I live in Southern California (10b) and have clay soil that stays wet after heavy rains. I want to plant two dwarf avocado trees (Wurtz and Holiday) in my small backyard in a 8'x4' by 2' tall raised bed. I am thinking of filling in the raised bed with 18" of soil made from potting mix, vermiculite and coarse sand in the ratio 3:2:1. The top of the rootball will be 1-2" above this soil mix. On top of the soil mix will be 6" of home made compost made from garden waste, leaves etc. Any advise? Will the soil mix be too fast draining? Should I mix in small quantities of my native clay? What about sphagnum peat moss? Any advise will be greatly appreciated. This is my first attempt at growing avocados.