Answer: Butterfly bush is sometimes root hardy in zone 5. They have the best chance in a protected location that is sheltered from winter wind and where the soil is very well drained. To increase the chance of survival, mulch heavily in late fall after it stops growing for the season. In the spring, cut it down to about a foot tall. In late spring to early summer you should see new growth if it is still alive. It may come from the old wood or it may come from the roots or both. It blooms on new growth so this does not reduce flowering. Good luck!
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