I amended the soil with peat moss, and rotted wood chips. I also added aluminum sulphate. This fall, I've added shredded leaves and pine needles. The only thing I didnt do, was the one step I should have done: a soil test. But, I was told it might tale 2 months to get back, and my blueberries were due in weeks!!
So far, just planted this spring, the ones in the ground, and ones in pots are running neck, and neck--with one exception. One pot, the berry just didnt thrive, grew, but didnt thrive like the others. My pots are about 3' across top, and waist high.
I planted Patriot, Darrow,Kablooey,and Dwarf Tophat. So, yes, 2 of the six were for containers-and its one of these thats not doing well.

It is important to get the soil right in the beginning. I planted two at my friends house and I can't get them to grow. He has clay soil and no rocks. Mulch on top did not help. You need to really mix in the humus and peat or whatever before you plant them. Also mine at home are good but I have one that is a later variety and sour. Finding a good tasting variety is important, of course.

Dorothy's Digs (local greenhouse) grows them in a row by her apple trees and they look wonderful. I asked her what she did special and she said nothing! Maybe she waters her garden regularly and they are close enough to get that extra water. I know the roots are never supposed to dry out. I have had maybe a handful from mine....very slow.