Jan 23, Even if your butterfly bush doesn’t dieback during winter, prune 6”” above the ground in late winter to ensure proper growth the following spring. If you have a Buddleia alternifolia, prune your bush back hard to about ⅓ of its size immediately after it flowers in the early summer%(57). Jun 07, Wait to prune your butterfly bush until late winter or early pruning burtterfly bushes.
Cutting the stems back in fall can make the shrub more vulnerable to freeze damage. The shrub will tell you when to prune by showing new, healthy looking leaves forming low, near the plant's base.