I can't think that your choice of vines are unsuitable or that your cllimate zone makes any difference. And I should think most of the shrubs you have chosen would be particularly well-suited to tolerating a clematis.

I grew all manner of clematis into trees and shrubs in my old garden and never had an issue with either the host plant or the vine. And some of the clems were big, robust vines (C. montana, orientalis, terniflora). They only got pruned at the appropriate time of year (late winter) if they got pruned at all. I can only say that any evergreen hosts were those that had a pretty branchy, open growth habit, like rhodies. No conifers.

Well, I'm really at a loss to explain it, then. There must be some factor I'm overlooking - it can't be only me. Thanks for the input, though.

I don't grow Mme. Julia Correvon, but I know that both Huldine and Betty Corning are pretty large plants. Perhaps they are creating too much shade for the size of the shrub or tree? Are any of the clems you have on shrubs less robust? If not, perhaps trying a smaller or more sparsely foliaged clematis would make them coexist better.

That may be another factor. I've grown the clems up the outside of the plant on the dwarf arctic willow and the juniper. The crabapple, though, had the clem planted close to the trunk and so Huldine went up pretty much straight, inside the tree. That's where the crabapple didn't grow many of its own leaves. The rest of the tree looks good. I always intended to spread Huldine out so it didn't all cluster in one place, but it frequently got away from me. I wonder whether other gardeners shove, I mean, encourage, clems to grow largely inside a plant and only peek out here and there and wonder whether they're better than I am about spreading the clem out so it doesn't impact the host as much. I appreciate all the feedback, though. I'm the only gardener in my family, so it's nice to discuss ideas with others who have different experiences.

I have had problems growing Clematis up or over other plants. I have had bare spots and even death. It isn't just you.

I currently have Huldine up a purple leaf plum but it is a scraggly tree so I don't care if it hurts it.

I've got to go wrangle Juuli over the barberry which is makes bare in spots but better that than the hydrangea it is now laying on due to wind.

Alionushka killed a hebe. Petite Faucon killed a caryopteris.

Thank you - I was starting to think I had some strange jinx!

My clematises make bare spots on bushes too. Half of a juniper is bare from Pink Champagne, Spirea is not killed yet, but is heading in that direction, thanks to Hagley Hybrid. Sweet Autumn grows up an obelisk, till it reaches the top - about 10' high, then reaches over and climbs a mature spruce tree. Its branches are bare in that area. The only coexistence that seems to work is growing them up a trunk of a tall tree with some fencing wrapped around the trunk.
Grow

I've never tried that, but was hesitant to take a chance with a large tree, wondering whether the clem would hold in too much moisture or something. I think I'll stick to non-living supports for now or plants I don't care too much about, like willows. Thanks for all the feedback.