While most hydrangeas seem to bloom in summer, some bloom late summer into fall like the paniculata that we have. These delightful shrubs were as overgrown as the rest of the property last year and took over the whole porch area. I cut them back by about a half, while still leaving some taller branches, and will finish this winter with the other tall branches. They are wonderfully vibrant and green all summer then put out these amazing flowers at the end of summer.
The bright white slowly matures to a delicate rose pink which will stay pink if you pick and dry the bloom. Clearly these two bushes have different amounts of sun as one is already in the mature stage and the other still in the white phase. Lovely bushes anyway and will look much better next summer when I have finished the pruning.