Cutting back clematis vines helps them, not hurts them. They love rough treatment lol!

In Petaluma I cut mine back within a foot of the ground after they finish blooming I get a second blooom flush on most of them. I don't have a picture from this year but here are pictures from a couple of years age.
This is Carnaby the first part of July after I cut it back:
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And here it is in September:

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It's in a half barrel because I wanted it in the shade so it wouldn't fade so fast and that area is full of tree roots.

Interesting. I have a couple questions.

Does this kind of severe pruning in early July work with all classes of clematis, or just with Class II? (Isn't that Nelly Moser's class?)

Would it work to prune like this in August, or is that too late in the season?

Thanks,

Kate

Kate I can't answer for your climate. Davidk hort mentioned an area which must have a climate like the one here. We seldom get a hard frost and the climate is moderate year around. I cut them back anytime except for class 1. Someone with a climate like yours would know what you can do. I know that Jeanne in Texas cuts hers back and gets 3 flushes a year on some of them.

I my z5 climate I can only cut back very vigorous growers and bloomers like the viticella and expect to get another flush. Even then I have to keep them watered and fertilized in order to get this, and I don't always have the desire. In z6 you have a bit more leeway.

How I'd do it: just as a clematis is finishing up its bloom season, cut it back by 2/3, give it some fertilizer, then keep it well watered. Choose a ones that grow well for you.

Thank you, bob and michael, for the advice. I'm going to try michael's procedure next summer. Sounds good!

Kate