I'm not sure I understand why they're leaning. Is the soil actually shifting? Or is it shady on one side and they're possibly growing toward the sun? Or possibly something else?

If it's the soil I think it would be a good idea to dig them up and replant them in a position where the soil will be stable around them. If it were me, I'd do it now while they're still dormant. I'd cut them down first, and then dig them up and replant immediately---but only if the soil is dry enough to be workable without compacting it too much. Then water them in well, and don't water again until you start to water other things in spring.

If you think it's some other problem, let us know,
Skybird

Couple of other thoughts. I've never noticed buddleia having an issue with growing toward the sun, and although it's certainly possible, they've always been pretty tolerant of most situations for me. Lack of sun they flower a bit less.

How long has that berm been there? It could be settling or shifting. Ground in this area is far from stable and I would imagine yours would be the same.

Another possibility is creatures tunneling under? I've never had voles or other such rodents, but I know people who have, and if they have a network under your berm, you have a problem. Even prarie dogs.

I'd definitely dig them up before they start to leaf out. It's also possible something has damaged the root system on one side, and as roots die, they loosen. You won't know til you dig.

I'm going to put in my two cents worth here. Where do the prevaling winds come from? My first thought is the wind is redirecting the growth. You would need to put up a wind block. Even trees out here on the plains have branches only on one side when they catch a lot of wind.

Billie

Do you prune them? You can cut them down by 1/2 or 1/3 in Spring and see if that helps. I hard prune mine every year.

Cheers,
Michelle

Thank you all for your comments!

After reading them, I've concluded that the problem is most likely shifting soil. Before planting the buddelias, I built up the area where they're planted to make it level with the area along the back fence where I have a row of syringas, and to make the area a bit higher than the path. There's nothing to stop the soil from migrating toward the path.

Perhaps the problem is that I have them planted too close to the edge of the path (which is nothing more than the same kind of soil, covered in mulch, approx 4-6 inches lower than the level of the "berm"). There's less than 12 inches of level ground in front of the bushes before it starts to slope down. Is it possible that I also have them planted to close to the fence (which runs along the north edge of my yard and is covered in grape vines in the summer)?

Maybe I should do this - prune them to 18 inches or so (as I usually do in the spring), dig and reset them, then either extend forward the raised area or raise the path to this same level?

I included photos below in case that prompts any add'l thoughts. Sorry the second one is blurry, but it gives you an idea of how far they're leaning in comparison to the fence/path, and how much lower the path is than the berm.

Thanks!

Mags

Mags,
I wouldn't attribute the direction of the plant leaning to soil shifting unless it was at an extreme grade (by the photos it doesn't look like much). The nature of Butterfly Bushes growth is arching and open.
Since they been in for two season, you can safely trim back about half (or more)and utilize your fence as a trellis or use stakes and train the growth much like a grapevine (kniffin two, four or umbrella system)and not a typical bush.
Trying to adjust the bushes without trimming will probably end up with involuntary pruning- breakage.

I have Butterfly bushes along the Eastside of my house that lean to the East and some on the Southside that lean toward the South. I love how they arch into the walkway with flowers during the summer.
They're thriving- you should be happy about that!

Ok, pics always help. What I remember is that when I had my butterfly bush in Tucson, it was in an area where there was not anything behind it. No fence or anything taller than it and it was straight and happy. My grandfather on the other hand planted a start from my plant against the fence (block but same idea) in approx the same positioning as yours. It did much the same thing. Leaned out like it was trying to escape the fence. Maybe move them out so there is a path behind them to access the grapevines too?

Billie

I agree with Pacu that there doesnÂt seem to be enough of a slope for the soil to actually be shifting, and based on what Billie said, I also agree that it seems like the fence itself is having some sort of an "interesting" effectÂbut I donÂt know how or why!

When you look down at the base of the plants, does the crown seem to be facing straight up? IÂm guessing it does! If thatÂs the case, I recommend cutting them all the way back to about 12" and then watch them as they start to grow out again to see which way theyÂre goingÂand if they still seem to have an aversion to the fence, I agree with Pacu to find a way to stake or cage them to keep them where you want them. You may find that if you cut them back hard each fall or spring, the new growth wonÂt tend to flop as much.

If you do decide youÂd rather move them to try them somewhere else, I still recommend you do it soon while theyÂre still dormant, and they should still come back and bloom nicely for you this year.

Skybird