Yes, it is possible to move perennial plants all at the same time but all plants prefer to be moved when they are dormant in late fall, winter or early spring. However sometimes you just gotta move when you gotta move. You can have a successful transplant even in the summer if you first soak the soil the night before. Then wait for a cloudy day or late evening to dig the plants with as much soil as possible around their roots. It may help to dig and set them right into large pots so the roots are not exposed to sunlight. Next replant at the same level into pre-dug holes that have been filled with water and allowed to drain. This ensures that the transplants go right into moist soil. You can use a slow release plant fool like Osmocote around the plants but do not fertilize them with a fast=acting fertilizer at this time - they just had major surgery - would you like big meal after a transplant? Next, expect some wilting as new roots grow. You may want to shade the new transplants with newspaper tents or umbrellas if the weather is hot. But remember, most perennials prefer that you wait and move them when they are under the anesthetic of dormancy. Could you possibly wait until October? Best of luck with the big move, Keep growing, Marianne Binetti