Slow Growth Blueberries

Year two on the blueberry transplants. I started with two, two year old plants and one three year old plant. All different varieties. I dug the holes and worked in peat prior to planting. Last fall, I put down a thick layer of pine straw collected from the trees in front of the house.
These plants get full sun from about 10am-7pm.

I thought I'd see much more height and width growth by now. They've had plenty of good rain and drainage seems adequate. Maybe they need a full three years before they really take off. I'll need to read up on the pattern. I know the soil is really tricky, too.