I typically whack them off about a foot up.

Every once in a while we will get a mild winter, such as the one just gone by, when our Buddleias don't die as far back as normal winters. Makes it quite tempting not to cut to the one foot rule of thumb, but having played into that temptation a few years back, I will always cut mine back.

Basically, if you let it go and just trim off the dead tips and such, this thing will grow into a monster. It will also produce less blooms - blooms on new wood. If you get a typical cold winter, then next year you will have the task of cutting down those huge branches since it will have died back to the ground. You'll need someone with good biceps to get it done. Seriously!

I have to go with Spazzy - cut to a foot from the ground. I did 7 of them on the weekend and just have one more to go. They all showed growth up to 6 feet. So tempting!!

I kind of thought what you described might happen, tiffy, so thanks for sharing your experience. Even though I don't see any growth as low as a foot, new branches will come out of the stumps? Thanks, too, for the reminder about "blooms on new wood" - that makes a big difference!

excuse me for an OT insert everyone- tiffy, we are 2-4 wks ahead of a normal Spring here in Ma.(It's sooo exciting!!!) What about you up there?
best,
mindy

I have an old Black Knight that is sited in my front garden near the driveway and street growing under pretty challenging conditions - full sun, dry sandy-ish soil, exposed to severe northwest winter winds. The thing is doing great! I am very pleased with how this particular cultivar performs as we are close to the borderline of hardiness for Buddleia in our zone and this is not a sheltered location at all.

The Black Knight grows about 7 feet tall each season, which is tall enough as it is - can't imagine how large it would grow if it wasn't cut back. I cut it down sometime in April when the new shoots appear from the old wood. Just above the green buds so it's about 12-16" high. I also thin out some of the weaker or dead stems and maybe even remove some of the shoots. Btw, I also have a Pink Delight which is not as vigorous so I don't usually cut that one down as low as the Black Knight.

Here's what it looks like this Spring after it got its pruning -

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Wow, terrene, thanks for that photo! Yours is way, way ahead of mine. I live in north central MA on the NH border, and I only have a few tiny sprouts, mostly on upper branches. I think mine are slowed too because they are planted next to a barn and are shaded in the mornings. But even in past springs I don't think I've seen as much growth from the base as you're getting. That is one healthy looking buddleia you've got there!!

Hi Vicki, yes that Buddleia is very happy this year for some reason. I don't remember it having so many shoots in past years. I will have to thin out those at the base of the plant. Also it is going into its 6th year and it was in a large pot when I bought it. It grows up to look like a shrub, not a perennial, which pleases me because it offers some privacy and wind-screen.

I am in metrowest Boston, and you are probably at least a half zone colder. Didn't you guys get some snow last night which we didn't get here? Perhaps your plant is not so happy where it is?

Somewhere I remember reading that the dark-colored butterfly bushes are hardier than the light ones.

Vicki, I am probably near you and my buddleias don't look like terrene's either.

No snow up here but pretty chilly. We were definitely 2 weeks ahead of schedule earlier, but I think this cold spell will even things out.

I have Blue Nanho for many years and Black Knight for a few years and both of them do fine. I cut down to 6"-12" as soon as I see tiniest new growth.

Not sure if its related, but I have seen a couple of cases where buddlieas died when they were NOT cut back.

terrene, we had snow flurries Wed. morning, which I thought was bad until my cousin sent me pics of the snow in Vermont. They had to get the shovels out!!

wendyb, thanks for your comments too. I don't think my buddleias are in perfect spots, but they've done well enough the past couple years. Thing is, the first two years I tried growing them I cut them back in the spring and they died. I hope it's a timing thing and I was just too early before cause I'm going to cut them back this weekend and hope for the best.

oo. I trimmed mine a few weeks ago (but nowhere near 12", lol) 'm going to cut mine back right now and try rooting the branches. Maybe I can have a whole hedge of butterfly bushes next year. :)

I am in Ellicott City, MD and very nervously pruned my Black Knight budds , in first week of March, to 18" above ground. They were already 2 feet high and this meant cutting off new growth. Should I have done this?? They are 8 years old and prolific, but I have only been pruning them, now that I've learned about what to do , for the last three years. They grow to eight feet . What happens if I don't prune them?? I like them wild and woolly, but am determined to stick with "vigorous pruning" to get a more compact look. We use them for shading our windows from southwest sun - they are on a southwest aspect, sheltered by a wall behind. I could not get my pictures to insert, sorry.

They should be fine. When you deadhead, or as the primary flowers are fading,you see the next ones growing in leaf nodes. I deduce that even if you pruned pretty late, that bush has lots of reproductive potential. With your long growing season, I'll bet you still get a great rebloom after you deadhead the first spent flowers.