I am sorry for this delayed reply to your gardening question. The spring rush has brought a deluge of questions and we are working hard to catch up!
You only need to cut them if there is winter damage. Then do the pruning in late winter or early spring and only cut back as far as the damage. In your area unless there is significant winter protection they will be killed to the ground each winter. Mulch the base well to protect the base of the plant so it can resprout.
Thanks for the question. Best wishes for a wonderful gardening season. Please stop in again soon!
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