I've just about given up on planting fruit trees here. Of the 6 I planted 10 years ago, only 3 remain, and only one of those is actually doing well. Getting the hole right seems to be the biggest issue. If you don't get it big enough that you can add enough good soil, the clay acts like a bowl and holds water. Not big enough and the roots don't have room to expand, because the clay is super hard in the summer when it drys.