Decades ago, I had an Alice that lost a branch due to the dogs (my guess).... I do not recall exactly when this happened though. It does not feel like it was "cold" so maybe Spring, Summer or early Fall. I dipped it in rooting hormone, planted it and it did just fine. About 1-2 years afterwards, I moved. My winters are mild with dips to the 5F-15F digits in January, Hydrangeas are very easy to propagate.

Hydrangeas are generally easy, but oakleafs are considered by some to be a bit more difficult than the rest, and climbing hydrangeas even more so.

That said, I rooted 4 (of 4 attempted) hardwood cuttings of an unknown (older) cultivar of oakleaf hydrangea this winter, indoors under LED and a homemade fog system, with bottom heat and rooting hormone. Took just under 3 months to root.

I'm planning to try softwood cuttings this spring/summer as well. I haven't had any success previously with those, but that was when I was just using a typical humidity dome setup. We'll see if it goes better under fog.