Climbing hydrangeas are large vines with deciduous or evergreen leaves, which cling via aerial roots. In seedlings, the stems branch and creep along the ground until they come upon a vertical surface (tree trunk, wall, etc.), whereupon side shoots grow upwards and attach to the surface. Climbing hydrangeas therefore make excellent ground cover in shady environments. Once heading up the tree, climbing hydrangeas tend to stick to the trunk and seldom spread out into the canopy. They can develop substantial trunks of their own, a significant weight for the host trees to endure.

The climbing habit evolved twice in Hydrangea. The most familiar climbers are members of two sister sections, Calyptranthe and Cornidia, with a shared ancestor.  Perhaps the best known of all climbing hydrangeas, deciduous Hydrangea petiolaris is what you’ll get at the nursery if you ask for a climbing hydrangea. Native to Japan and Korea, it’s a member of section Calyptranthe, as is its sister species, H. anomala, from China and Taiwan to the Himalayas. In the much larger section Cornidia, you’ll find most of the New World climbers, including the Chilean H. serratifolia and the Mexican H. seemannii. From Taiwan, H. integrifolia also belongs here, despite the disjunct distribution. Most other Cornidia are too tender to grow in the US. These are massive vines with evergreen foliage and should only be attempted where a suitably large tree is available to host.

Photos 1 - 5: Hydrangea barbara, Hydrangea hydrangeoides, Hydrangea integrifolia, Hydrangea petiolaris, Hydrangea seemannii.

The other group of climbers were previously considered to belong to other genera, now lumped into Hydrangea. Schizophragma contains several deciduous vines from Asia. They produce fertile and sterile flowers, as in Hydrangea, but the sterile flowers have one enlarged sepal, rather than four large petals. Best known is S. hydrangeoides, now known as Hydrangea hydrangeoides (“the hydrangea that resembles a hydrangea”), a floriferous vine with lovely yellow fall foliage. Pileostegia has two evergreen species in Asia, and it is P. viburnoides (now Hydrangea viburnoides) with honey-scented blooms and no sterile flowers that is most often cultivated. Decumaria has one species in China, but the better known is D. barbara (now Hydrangea barbara) from the U.S. Southeast. 

Climbing hydrangeas are an excellent addition to any woodland and when grown up large conifers such as Douglas fir, make a towering statement in the garden.