maybe a type of scale. see photos at the link below. these pests can be controlled with applications of horticultural oil. Here is a link that might be useful: pulvinaria

Agreed. I hope somebody like Tim Wood can figure out a way to do with this what he did with Tuff Stuff, and make one that blooms on old and new wood. Although very hardy, it's no guarantee this will bloom under all conditions. Yours looks good though..

gfleatham, I've been enjoying the info on various hydrangeas you've been adding and appreciate the accompanying photos. Any chance you'd be willing to add your zone & general location to your profile so that they post by your name automatically? TIA Houzz doesn't make it easy to figure out how, so here are directions: Go to Your Houzz in the upper right of every page, click Edit Profile, and on the left side click advanced settings. Well down the advanced settings page is a blank labeled Climate Zone for Garden Forums along with a link to find your zone. You add info on your state or the nearest large city since zone only relates to average coldest winter temperatures. Then return to the top of the page and click Done Editing.

I would plant it in the ground once it goes dormant OR pot it and keep the pot in the ground during the winter months (this lets you extract the pot should winter become very, very cold unexpectedly). If your winter appears to be unusually cold (long term forecasts are not out yet), bring it into the garage or cover the shrub with lots of mulch to protect it in the rare chance that temps go down enough to risk flower bud damage. Temps around -4C, more or less would start to bother me and I would create a mound around the little shrub. I have planted cuttings of mopheads, serratas and oakleaf hydrangeas of that size with no issues. My concern is usually that temps here tend to go up and down during winter and then they crash so, watch out for similar temperature "behavior". If that were to concern you a lot, feel free to keep it potted in the garage all winter instead (during winter). I noticed some -4C temps (or lower) last winter in your area. December was the coldest month in winter with frequent low temps around -3C thru -6C.