It depends on how long they've been planted. If they're more than 2 years old, personally, I wouldn't move them. They do resent transplanting, but it can be done with great care. Plus, they shouldn't get any bigger, especially since in our zone they need to be pruned back hard. I've had a white one for 11 years now, and I can only prune it back to 3' since the trunk/base is HUGE. I'll have one heck of a time removing it if/when it dies! It gets to the same height every year, about 7'. That one is also in an awkward place, close to the sidewalk, and tends to get ratty looking (controlable with diligent pruning) and loaded with carpenter bees, but everyone admires it when they're walking/driving by. I don't regret planting it in the front of the house, it certainly does stand out and gives people a nice showing of bees & butterflies.

I'd trim 'em back, if they are too big and busy. :)

I transplanted one of mine a couple weeks ago....it's not doing so well. There's only one branch left w/ green on it. But then again, I moved it from a spot it was only getting morning sun, nice soil, to full sun, crappy soil!

I want to move my other 2, but only a few feet. I wonder if that'll have as much of a drastic effect on them.

Don't get me wrong; I've moved a few buddleias. They will sulk, to the point where you think you've killed it. That happened with my "Royal Red". It did return the following year, luckily. I've also dug up babies in bloom; potted them up, sulking horribly, but they rebounded. Well, one really hasn't. I moved a baby last year, and this year it's smaller than last years. Same crappy soil; I'm not a big fertilizer. I have never moved a well established one.
Cutting them back is fine to keep them in the shape/height you want.

hmmmm well maybe I should leave them alone! This is the second place for the Black Knight. The first place it didn't do well at all! I really think it likes where it is. Full sun and with the tarred driveway it gets very hot. I just wish these bushes had some interest during the winter.

I have a feeling though if I move them I will kill them.

Thanks all - I think I will just dig up the hydrandeas & weigelias instead.

So should I cut them back now or wait until spring?
I usually deadhead now and prune in the spring.

Chantel :-)

Wait until spring growth has emerged before cutting them back.

Butterfly bushes should only be cut back in late winter/early spring. If you still want to, that would also be the best time to dig them up and move them. The problem I always have is that the bushes have large shallow roots, many of which have to be cut to get the bush out. But I've moved plenty with success, never lost one. They will look bad for a bit, but usually rebound.