Climbing hydrangea, known botanically as Hydrangea anomala petiolaris, is a summer flower species that is woody in branching and uses air roots to grasp vertical surfaces to support itself and and climb. According to the University of Rhode Island, the species needs no pruning for blooming and healthy growth, but benefits from removal of dead tissue and can tolerate pruning for height and spread to suit the surrounding landscape.
Prune away any dead, broken, cold damaged, diseased or otherwise problematic plant tissues in the spring after the last frost has passed. Remove only damaged branches at this point in the year. Make a clean cut down to healthy tissue just above a leaf axil or bud or back down to the parent branch. Pull the damaged branch gently from the shrub and discard.
Harvest fresh flower heads for use in cut flower arrangements in the summer and deadhead the flowers left on the plant when they become discolored and die back. Cut down on the stem to the parent branch or just above a leaf node or bud to encourage new branching and fullness.
Reduce the size and sprawl of the hydrangea by cutting back the terminal branch tips to the desired length in the summer when blooming has finished for the season. Remove up to one-third of the live plant tissue but no more in order to prevent stress on the plant and shock from setting in.