When it comes to the Hydrangea paniculata, don't over complicate things by worrying about pruning. With all the breeding work that has been done in the last decade or two pick the variety that fits the space and assume everything will get a little bigger than the tag says. These are really no brainer plants. These are my observations with many varieties in my location (MN). If the spent flowers bother you, prune them off late fall through early spring. Get out the shears and do it. No need to fuss with hand pruners and each individual flower. Otherwise the plant will grow over them. Also, it seems like the the more lace cap type flowers tend to break off over the winter. Pruning them back will not significantly reduce their size in a given season once established. I've seen hard pruned plants grow taller than the unpruned specimen of the same variety. Right plant, right place. Hard pruning seems to create a later and more uneven bloom cycle on the plant. I prefer the plant blooming consistently around the whole plant so don't prune or just lightly. I haven't seen a consistent result of pruning and flop prevention. I think age structure are more important. Certain varieties with big, full flowers are more prone to flop with the right weather event. And with some of the new breeding in Hydrangea arborescens those of us in cold zones that don't want to deal with Hydrangea macrophylla even variation in sizes, colors, shapes and timing. Just no blues.

Well, I can only speak from my experience. As you can see from my pictures, I did a really hard prune. I am shocked by how beautifully it has grown back and prolifically bloomed. I don’t think removing them will hurt the appearance of the trees. If you want them to maintain a tree structure I would recommend cutting those suckers off either late fall or early spring. Most people say to prune in early spring but it can also be done in fall. Basically, the suckers are taking energy away from the development of the main tree trunk. Removing them will let the energy go into producing the tree, branches and flowers. Also, downward branches, weak/thin branches and crossways branches should be removed. Hope this helps! debra

Looking great! My Limelight blooms here in SE Michigan are at the exact same stage. Every day I peek outside to see if they're in their full glory yet - I'm getting impatient! :-)

Everyone seems to have a different POV on trimming your trees. 6 Years before a hard cut . The answer might be slighting different based on branching, but I think once the primary stems are around 3/4-1 inch thick or so and of decent length , I start cutting back hard. Don't think it would be 6 years though. I let the subsequent stems from that grow out, get a bit thicker and to the length I want, and then continue to cut back hard once thick enough . The second round of stem framework may be around the 6 year mark, but not the 1st IME, the thicker the stem, the new wood that comes out and blooms is strong enough to not be a flopper. With all this WFH time, I've been kneeling/crawling on my back to see how the new wood comes out of (old wood) stems to get some understanding on how energy flows......I've yet to form a consensus though.