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!
Unless they are very weak they can resprout from a severe pruning. The most likely cause of their lack of vigor are lack of adequate light intensity and lack of nutrients. If they were mine I think I would try a moderate cutting back right away so as not to remove all the foliage and then begin fertilizing them every 4-6 weeks through about mid summer. This will give them time to regrow and set bloom buds for next spring.
Thanks for the question. Best wishes for a wonderful gardening season. Please stop in again soon!
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