18 ft high buttery fly bush
How and when should I trim this butterfly bush?
Certified GKH Gardening Expert
It's completely up to you! This bush responds well to any type of pruning at anytime. Take them down to whatever is necessary for your case. Here is an article that will give you some information: https://www.gardeningknowhow.com/ornamental/shrubs/butterfly-bush/butterfly-bush-pruning-how-to-prune-a-butterfly-bush.htm