Pruning an Endless Summer hydrangea right after it blooms gives it a better chance of producing more flowers. Never prune a hydrangea when buds are still in the process of opening.
If you're simply shaping the hydrangea, remove no more than the top third of the plant. Pruning a hydrangea to the ground is only an option when you are attempting to rejuvenate it.
The Endless Summer hydrangea is ideal for colder climates because this hearty plant still blooms even when its old stems are damaged. The Endless Summer hydrangea is bred to bloom on both old and new growth.