I just came across some pictures that I should have published with the “Digging the Holes” post.  Anyway, after Mike dug the holes by hand with the post hole digger, he went back a few days later and drilled them with an auger (?).  The pictures show the length of the auger and how far he drilled down.  Approx 2 ft.  We wont plant the plants that deep but when we push the dirt back in the hole (abot a foot) it will give the plant some breathing room and better drainage.  The roots wont have to struggle so much to grow.