In the growing stage, before blooming, I notice that my Black night butterfly bush grows very leggy, straight-up shoots. I want to trim it to make it bushier. But I read that it won't bloom if you do that! That sounds a little nutty to me, but I don't want to take a chance. Is it true? Or nonsense?
One method is to prune whole thing low each year as growth begins at end of winter. This results in fewer stems with larger flowers. However, if you want a bigger top with more branching you will do minimal pruning. Snipping individual shoots a bit won't have much effect on the overall presentation, unless you overdo it.
Butterfly bush is very vigorous, if you prune it way back during active growth, you will lose blooms for a while, but it will quickly recover. Typically Buddleja is pruned back hard (to 30-45cm) while dormant in late winter.
