Here in zone 5, Butterfly bushes die back to the ground so in the fall I cut them back so they look less scraggly and then in the sping I cut them as close to the ground as possible. My new growth starts from the base of the plant and grows rapidly once the weather stays warm. My new growth is about 6" right now.
Hope this helps!

I'm one who is cautious. I will cut them back to 6 inches from the ground in spring once the new growth starts. Cutting back to the ground, well, we might still get a freakish killer frost which could kill the whole plant as was the case two years ago. I had just cut two down to 6", but the third I had cut to the ground. It didn't survive a frost we got in late May which was out of the norm.

Having said that, I have a third which I don't trim back at all until June. Even though it's the same as the others, it's in a different spot and sometimes will grow right from the previous year's branches, but not from the ground. Looks like it's up to it's old tricks since it's doing just that this year, yet the other two are bursting from the ground.

Go figure!! :O)

Whoa....they start new growth from the ground!?! I read to cut them back and they grew new growth from the cuts. Also that the branches appear dead till late may. Before the cold snap, I had new growth on mine, on the old branches. That died, and now, I have stuff growing at the base, at first I was pulling it out thinking it was weeds. I stopped just in case. I'm so glad I stopped now!!! I would've killed them completely!!! Thank goodness for this thread!!!!!!!!

Kek,

That new growth on the branches which died, well, don't be surprised if you get new growth from those points again. Mine does that.

Nicole.

I have two Butterfly bushes, one 6 years old (purple) and one 3 years old (pink). They were purchased small, but are not "homegrown WS". My husband cuts them both to about 2 ft from the ground in March. They bud out from the trunk that is left, and from the bottom too. The purple one gets about 8' tall and 5' wide, the pink one about 5ft and 3ft wide with lots and lots of flowers. Hope this helps..... I have a feeling that "the right thing to do" may very well vary by zone.

Nancy

I cut back mine once I see new growth each spring. Sometimes a freak late frost nips that new growth after I've cut them back but they repsout again.

Mine regularly sprout growth on the old branches...I never cut them back or trim them until the growth is well under way.

Thanks for all the great input, see I told you that WSing people are smart. I think Nancy is right it must depend on what zone you're in. I think I'll let mine go for another week or two to see if I get any new growth off the old branches. One of the "experts" on another site said that cutting back will give you more blooms but that the blooms will be smaller. My pink bush has much bigger blooms, which I really like so I think I'll wait a while to see what happens.

Strouper

I wish I could let mine "go free" and attain their true mature heights. A fews back before they underwent remodeling, the old butterfly garden at the Bronx Zoo had a hedgerow of Black Knights that were well over twelve feet high; the flower panicles were about a foot long. Stunning!

I bought three butterfly bushes last late summer on clearance. One of them I cut back a short while ago to 12" because I read that the branches will help support the new growth....it is growing really well. So far the other two haven't shown any growth yet and I didn't cut them back. I wonder if cutting the first one back prompted it to grow or if the other two just didn't make it. Time will tell.

Bonny

Strouper,

I also think that zones have something to do with it, but also the kind of winter you have and where the plant is situated. So many things come into play with this plant.

Trudi,

The one which I have which grows from the branches grew to 10 feet last year and was huge. They are quite stunning when they are that size!

Bonny,

One trick I use to find out if they are OK is to scratch a bit off the branch and see if there is green underneath. Do this at about the 6" mark, and remember that if one branch has 'died', another may not have. If there's no sign of life in any of them, trim back, but leave the plant there for a while yet as it may still grow from the base.

I've WSn a few (they're late germers, so nothing's happened in there yet), but the two that I had (Ellen's blue, and Black Knight) from clearance last fall were doing nothing. Impatient me dug them up to see if there was anything going on under there, and the root system seemed completely gone, so out they came.
I'll replace them early this season, and try to get them settled in before winter. I think a lot of the problem with some clearance items is that they simply have been in the pots too long, and get root-bound, and no matter what you do to save them, it's too late; they're gonners.

So tell me, is the green at the base of these to butterfly sticks (they certainly don't look like bushes right now) new growth?? I too bought mine on clearance at the end of the summer. They looked really sickly when I planted them, but once I learned about pinching off, they really performed. But I transplanted them 2 or 3 times, so who knows whats going on now. I'd like to move them again, but I'm afraid it'll be too much for them.

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It looks righ from above to me, but if you do a side shot it will make it easier to ID.

Looks like it to me also. Mine was just starting to come up last week and it is already almost a foot tall!

Strouper

so do i cut off the old branches then? or wait to see if they come back to life?

kek19 I'm going to wait until this weekend and then cut anything off that isn't showing new growth. I'm mainly going to wait because I probably won't have the time to do it until then. I can tell already that my Black Knight bush is going to get all of it's growth from new growth out of the ground.

Strouper