If not cut back as directed they will get much too big and look quite ugly. Al

Thanks for the info, Al. I'm thinking ahead to how much more work the gardeners will have next year since I planted a LOT of new things this spring. :) If the Buddleias can make do with just some trimming to keep them neat, that would be great. But if it's really essential that they're cut back, that's okay.

IMO they are a high maintenance plant.
The quicker you deadhead spent flowers the more flowers you get which can be weekly. The spent flowers are rather noticeable and I guess could be considered ugly.
I cut mine back to about 12 inches every spring. It keeps them fuller and looking the best they can be. They grow very quickly 4 feet in 5 months.

I'm interested in pruning my butterfly bushes. I have one (common purple b. davidii) that I planted last summer from a five-gallon container and it's now over 10 feet tall...one of the woody "tree trunks" is nearly 3 inches thick. I'd like to get it down to a manageable size. This thing has at least 1000 blossom clusters to deadhead...and it takes a LONG time to do. I also have a smaller pink butterfly bush that's grown by leaps and bounds this year. (also planted last year from a one-gallon container.) It's close to 6-7 feet tall and also is covered in blossom clusters.
I DON'T want to take them out...I love the scent of the blooms, and they keep my garden full of butterflies and hummingbirds.
I'm in Modesto.

Thanks.

Right now I cut mine down to about four feet. In the spring I will cut them down to about a foot high. I learned not to do that this time of year, when I did, and got a case "slime flux",which nearly killed the plants completely. Al

Cut them back the first year, and every year thereafter, and you can use a pair of secateurs...

or

Skip a year and prune them back with loppers...

or

Skip two years and prune them back with a bow saw...

or

Skip three years and prune them back with a chainsaw.

ROFL @ dick sonia...the biggest "trunk" is probably gonna take some serious chopping...it's bigger than I'll be able to cut with my loppers.

From what I've been reading, February should be about the right time to prune these back...right?

OR, should I prune them back in stages? some now, some next month, etc. until I get them all pruned back...then cut them to about 1 foot tall?

Thanks.