I have been doing this for a very long time. I have some in my garden that are twelve years old. I too am in zone 5a, Live on a farm in a very high and windy area. They have not suffered one bit. Have a 350 ft x 15 ft perennial border that never gets the hose unless it is really in desparate need of liquid. Lots and Lots of wood chip mulch and they thrive!
If you see them reduced grab all you can, watch them thrive.