Hydrangea petiolaris, a climbing hydrangea, is a species of flowering plant in the family Hydrangeaceae native to the forests of Japan, the Korean Peninsula, and the island of Sakhalin in easternmost Siberia, northern Russian Far East.
Hydrangea petiolaris is sometimes treated as a subspecies of the closely related Hydrangea anomala from China, Myanmar and the Himalayas, as Hydrangea anomala subsp. petiolar. The species Hydrangea anomala differs in being smaller (up to 12 meters (39 ft)) and having corymbs of flowers up to 15 cm in diameter. The common name Climbing hydrangea applies to both species, or to species and subspecies.