Flowers will always appear only at the terminal ends of branches. This is why pruning (or better, the lack of it) and winter dieback from cold are so critical wrt flowering. Whether new side branching originating from old growth will produce flowers or not depends mostly on the climate and cultivar. In my very mild climate with a long hydrangea blooming season, they often will. Otherwise, I think you may have to rely on both old and new wood bloomers for this to happen.

I’m in the same boat. i now bind them up, then slip on cloth tubes i sewed and stuff with leaves. i use clothespins to secure the top. An attractive look:)

Thank you gardengal48, that's exactly the detail I wanted to know about. Looks like I'll go big with the protection then!

kitasel2 that's a great idea, how does it do with snow - does it tend to shed it? I was thinking of using t-posts from my tomatoes to hold a plywood roof, then some type of wrapping and stuffing like you're talking about. But if snow isn't much of a problem, I could skip the 'gazebo' part.

I've skipped the protection. IME, things stay too wet, and the -old wood- stems wet rot if the leaves remain too wet

FWIW, the Let's Dance Series has been pretty good for me, in terms on - bloom on old wood-. I've gotten flowers out of lower 1/2 stems down, etc branching. For example, I've have some snow damaged canes that were reduced to half it's length. Was pleasantly surprised I still got flowering buds off of them this year.

After many years of struggle with many mac cultivars I gave it up. There are SO many nice arborescens, serratas, and paniculatas that me wasting any more energy on macs seemed absurd. Tearing out that last one felt great!