While there are many varieties of the well-known hydrangea shrub, only two varieties of true climbing hydrangeas exist. These vining hydrangeas make excellent woodland ground-cover, though with their clinging, hairy tendrils they easily climb trees, over fallen logs and onto stumps. Unlike many other vines, climbing hydrangeas do not choke their living host trees.
A North American native plant, D. barbara is the earlier blooming of the two hydrangea vines, with small, loose clusters of white flowers emerging in late spring. Vines will grow up to 40 feet, and are commonly found in the forests of the southeastern United States, as well as south into Florida and west into Arkansas and Louisiana. Plants should be located in a slightly moist, partially shady site; though it will grow in sunlight, Decumaria does not tolerate drought.
The plant is valuable for winter landscape interest, as well. Mature vines display a shaggy, cinnamon-colored bark. They can be planted as an alternative to English ivy or Japanese honeysuckle.
A climbing hydrangea native to Japan and Taiwan, H. anomala grows slowly, but may eventually reach more than 60 feet over several decades. In midsummer, large flat clusters of fragrant white flowers ringed by larger sterile flowers appear; a single flower bunch can be 5 to 8 inches across. Like D. barbara, H. anomala features shiny, dark green leaves, which fall in autumn to reveal a peeling cinnamon bark in the winter months. Because it can grow to immense sizes, a very sturdy support is necessary for this climbing hydrangea. Plants may become aggressive with age and require trimming.
The planting site for H. anomala should be moist and rich, and somewhat shaded during the summer months.
Japanese Climbing Hydrangea, Schizophragma Hydrangeoides
Several varieties of this Japanese climber are available through commercial nurseries. Though not a true hydrangea, this plant is often mislabeled as a climbing hydrangea at nurseries. Culture requirements are virtually identical to true climbing hydrangeas: moist, rich and partially shaded sites work best. The leaves of S. hydrangeoides are larger, lighter green and less glossy than other climbing hydrangea vines. Flat, showy white flowers appear in early summer, and the bark in the winter months is reddish-brown.
Like true climbing hydrangeas, the Japanese hydrangea can grow to 30 feet, and easily climbs walls, trees, pergolas and other structures with ample crevices.