Hi Matthew and thanks for your question about pruning your madrone trees. I actually have never heard of pruning a madrone because they have such unique growth patterns and are subject to a leaf blight that stressing the tree may encourage.

If you really need to prune your madrone, it needs to be done when the tree is dormant, late winter or very early spring, and as little as possible. Here is some more information on those very lovely trees:
https://extension.oregonstate.edu/news/native-madrones-are-special-northwest