I have one called Limelight, with chartreuse blooms in mid-summer that change to pink in the fall, then sort of beige as the blooms die off in winter. It has a more upright, vertical habit, but on thinner branches the weight of the blooms will tend to tip them over. I solve that problem using Y-Stakes. http://www.plantsupports.org/plant-support-img/plant-support-products/english-y-stakes-plant-support-2.jpg

You should provide them with water if a finger inserted into the soil to a depth of 4" feels dry or almost dry. You may also consider putting something to block afternoon sun as now is a bad time to be planting hydrangeas. Eventually they may be ok but on year 1 they tend to pout.

the better parts of nursery industry are trying to be aware of the problem and keep it under control...http://www.raemelton.com/bartletttreerese.html I have no less than 3 trees I'm worried about on this front now, following the sickening demise of a roundleaf beech that was almost 10 years old. It had hardly grown...no more than 3'...but I attributed that to it just being a slow growing cultivar. Dug it up, sprayed the soil off with a hose for 'plant necroscopy' - and found it had a puny, highly knotted root system. The beech had had a huge B&B ball, it would have been incredibly difficult to discover the problem when I planted it. But most of what I plant, about 90%, is container grown. For years I would just pull away any circling roots from where the pot edge was. Now I realize you're almost better off thinking of most things as "bare root upon planting". You really need to see the whole root system. So far, almost everything has been ok with this new, more aggressive approach. Most serious 'boo-boo' involved a Rhododendron arboreum delavayi that had grown in a pot for years, and actually was starting to root through the drainage holes. Though rhodies have a reputation for fibrous roots, obviously a tree-like species has to start forming some tree-like roots at some point. Apparently that point is very early on! They were very twisted, and when I tried to untwist them, 2 of them snapped. They were more brittle than most roots. As it was about to get hot, maybe I should have put this off until fall. But that was too much physical damage and the plant started an immediate decline. On the 'plants already in the ground for years front', I've already dug up a slow growing 'Dawyck Purple' and found it had the problem. I cut and even did a bit of sawing, to try to stop the circling...we will see if it survives this year with such aggressive fixing or not. There was a 'Dawyck Gold' I did this to about 4 or 5 years ago. It has started growing faster, but I wonder if I was aggressive enough back then....there still appears to be some minor knotting! I will post a pic later.

FrozeBudd, yes we had a rough season a couple of years ago, I think it was due to a wet August where the plants were in a lush growing green phase, then hit by sudden prolonged freezing temps. Leaves were frozen green everywhere, the hydrangeas never got to flowering. The following year there was significant dieback, I think they didn’t have time to harden off. Even my Snow Pavement rugosa rose died back to nearly ground level. That is amazing you’ve had paniculata hydrangeas hardy to the tips before. Usually about 2/3 or more of the canes die off for me, to about the snow line. Hopefully yours will return to their glory. I’ve noticed peat moss deteriorating over a few years, I may need to refresh my beds soon. Though the heat has really encouraged everything to flower early. Here is Firelight today, the colour is intense! Also not hydrangea related but here is some rudbeckia Autumn Colors which I was originally inspired by you to plant again. Nice to have some fall colour with these and the hydrangeas.