Another great thing about ‘Endless Summer’ is that is doesn’t care which way you prune it as much as the other "moptop" hydrangeas (H. macrophylla). The usual types bloom on year-old wood, meaning they carry their flower buds through the winter on those stems, and if you pruned too late (once the buds were already set) you’d have taken off the would-be flowers. The usual way to prune them to be safe was to wait till after bloom and just take out the oldest stems that have already flowered, since they were not going to do so again, and thereby make room for the strongest new shoots to develop nicely and hold the next crop of blossoms. Even following this carefully, sometimes in cold zones you lost your flower buds to severe winter weather, of course. ‘Endless Summer’ blooms on old AND new wood, so even if you got a little scissor happy, it will still make blooms this year. It’s also rated hardier than many other varieties. Basically I think the philosophy w/’Endless Summer’ is not to prune (except if there’s badly placed or dead/damaged/diseased wood) until it fills in nicely, and then you have your choice how/when to shape it. Some people also deadhead the spent flowers to make room for/encourage more. M. P.S.–I have to confess: I have never had a moptop Hydrangea in any garden I’ve made. Weird, but true. Oodles of the panicle types, H. paniculata…but no macrophylla, never.