It will depend on the severity of your winter. Here in Pittsburgh, most of the old wood is still viable and will produce new shoots and flowers, but the tips are likely to die back. In Erie, they will die back right to the snow line.

Since you're not certain, why not leave them un-pruned and see what happens.

I left my butterfly bushes unpruned for several years, and they formed a gorgeous high hedge that provided great screen.

Unfortunatly, they then died after a very cold dry winter. I don't know if the lack of pruning was a factor. Prior to that winter they'd seemed very healthy and happy.

They bloom much better when cut back around March to 15 to 18 inches. They should be pruned back before they bloom since they bloom on new wood. Maybe you want two rows, one for flowers and one for privacy.

I have always waited to see new growth to trim them above the new growth and have been taking master gardening classes this year and find that is the right thing to do this year with the sub zero temps there will probally be more damage than previous years waiting is best. Patty

Last year I cut some back quite a bit but a few I only trimmed. Those that I cut back pretty far had much larger blooms than the ones I only trimmed. They all had lots of blooms, so quantity was not affected, just the size.

I do have a related question. Around 2 of my bushes I have a few dozen volunteers popping up. They range in size from about 4" to 20". Should I prune these back at all? I was thinking to just let them be since pretty much anything they do will be new growth and should have some flowers.

Anyone have experience with this?

Thanks,

Jim

Sure, leave the new shoots. They should be the best ones.

I have always waited until I see new growth and then cut back both for cutting out larger older branches and for trimming right below new growth. My dad cuts them almost completely back and always comments that mine look so much better. It is more work because you have to look at each branch before trimming and think rather than just cutting everything.

I had Black Knight at our last house and always waited to prune back until I saw at least a tiny bit of green growth coming from the very bottom of the plant-usually by early May. Then I cut it back about 10 inches from the ground. The plant thrived and bloomed well every year. Last year, we had our home up for sale and I didn't want the edge of the landscaping without anything there for the couple of months that it takes for the butterfly bush to get some height (it was in the front of the house landscaping). I waited until it completely greened up, and just pruned dead edges. It bloomed very quickly but as vlf4230 said, the blooms were smaller but in generous quantities. My advice, wait until you see some green at the base and trim back to a foot or less.

Linda ~ Linlily