Take a look at the tree planting video
and the Sick Tree treatment
guides. How did you plant these shrubs? Are the roots wadded up still in the shape they held in the pots, are they planted too deep? What did you do with the soil when you planted - did you use the native existing soil or did you add a lot of stuff?
I usually find the smallest plant (1 gallon versus 5, 10, etc.) and plant, it being very careful to spread out the roots and not plant it too deep. You'll find that younger smaller plants will make up the growth very quickly and soon be as large as the 30 gallon plants but are a lot healthier and growing better. And a lot cheaper!