I wait until mid to late spring, when there are signs of new growth, to prune back my butterfly bushes. Then, I prune out any winter kill. And, take time to prune to give it a good shape overall so it looks balanced when the new spring growth comes on. Zone 5 and 6 gardens are a little bit different from the Southern states when growing butterfly bushes. With a mild winter, they will leaf out on the previous year’s branches. Following a severe winter or late spring freeze, the tops may dieback and they will regrow from the root. With that in mind, be certain to mulch your butterfly bush well going into winter.
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