|I have written in a similar question regarding lavender. Last fall I pruned my butterfly bush (black knight) back. We live in zone5 and had a more harsh winter than normal. Now spring is in full gear. We have been having warm, sunny days. The butterfly bushes show no signs of life. Did I destroy them last fall when I pruned out of the recommended season? (Can you tell I'm new to gardening?) What signs of life should I look for and how long should I wait before starting over? These were grown from bare roots last season and did exceedingly well. Thank you.|
|This plant may be marginally hardy for you, depending on the exposure where it is planted. A windy location would be the coldest.
Butterfly bushes are normally pruned in the spring. This allows the branches to protect the lower part of the plant a little bit during the winter. In a cold winter, they may die back to the ground and then regrow from the roots, in a milder season they may only need shaping. In any case, in late spring remove any dead wood and then be patient for signs of new growth.
This plant loves heat and sun, so it takes a while for it to awaken fully in the spring. It blooms on new growth of the season so you should still see a nice display. Next fall, apply a healthy layer of mulch over the root system to help insulate it.
Good luck with your butterfly bush!