What to do with butterfly bush in winter
Wondering what to do with your butterfly bush when winter comes? You're not alone! Here are three easy tips for success.
Fall is not the time to prune butterfly bushes. Though they may be lightly trimmed in autumn to remove any flower heads (and along with them, any lurking seeds) and neaten them up a bit, spring is far preferable for pruning. There are two reasons for this. One, leaving the plant intact helps protect the dormant buds that are waiting for next spring and two, waiting for spring, when the new growth starts to emerge, to prune gives the plant the chance to tell you exactly where to cut. Just look for where healthy buds are emerging, and cut just above them. No guesswork required!
While most plants benefit from a 2-3" layer of mulch over winter, this may exacerbate winter damage on butterfly bushes. The key to getting a butterfly bush through winter (especially in USDA zone 5 and 6) is well-drained soil, particularly when the temperatures are low but the ground is not frozen. Because mulch conserves water in the soil, heavy applications of mulch may lead to root rot. The best solution in cold climates is to put a light layer of mulch over the roots but instead of applying it all the way up to the main stem like you would on other plants, taper off the thickness so that the few inches immediately surrounding the center of the plant are bare and free of mulch.
Here's a definite don't for winterizing butterfly bushes. Fertilizer pushes new growth, which is exactly what you don't want to happen to a butterfly bush in fall or winter. If you want to fertilize a butterfly bush, the best time to do that is in early spring, when the ground is thawed. The best type of fertilizer to use is a granular rose fertilizer, like Espoma Rose Tone. One application in spring should be sufficient in most areas, though if you want more growth, you may make subsequent applications in late spring and early summer.
In short, there's actually very little you should do to butterfly bushes in winter. How easy is that?!