Climbing hydrangeas are flowering deciduous vines. These plants are true climbers, using the holdfasts (suckers) on their branches to scale walls and other structures. Native to the Far East, climbing hydrangea vines are best grown in USDA plant hardiness zones 4 through 7.
Taxonomy and Plant Type
Plant taxonomy classifies climbing hydrangeas as Hydrangea anomala ssp. petiolaris. This is a case where the Latin name (Hydrangea) is so commonly used that it essentially doubles as a common name (in which case it is not capitalized). Technically, you could also call them climbing "hortensias," an old common name that is seldom used today.
The Greek root hydr- in the name, hydrangea refers to water, as in "hydroelectric," "hydroponics," "hydration," etc. Meanwhile, angeon comes from the Greek for "vessel." True to their name, most species of hydrangea require a lot of water.
Characteristics of Climbing Hydrangea
Climbing hydrangea vines are large plants, sometimes reaching 50 feet tall or more at maturity. In early summer, they produce fragrant, lacy ("lace-cap"), flat-topped, white flower heads. These lace caps can be 5 inches or more in width and are composed of showy flowers on the outside and less-than-showy flowers on the inside. When they dry out, the flower heads turn reddish brown. Some gardeners cut off the dried flower heads for use in crafts.
The leaves are a medium-green color during the summer and turn yellowish in autumn. But these plants are not grown for their fall-foliage color. The plants' peeling bark provides some winter interest.
Planting Zones, Sun and Soil Requirements
Relatively few hardy flowering vines tolerate shade, but climbing hydrangea is one of them. In fact, in hot climates, they actually prefer a location with at least partial shade. Elsewhere, they typically will do alright in more sunny areas, if adequately watered. Climbing hydrangeas that do get more sun tend to bloom better.
Plant climbing hydrangea in soil that drains well and contains plenty of compost. Aim for a soil pH that is slightly acidic, and keep the soil evenly moist. Apply a 3-inch layer of mulch to help retain water in the ground around the root zone.
Newly planted climbing hydrangea vines are slow to grow and slow to bloom. But there is not much you can do about it other than to start out with the largest plants possible (of course, you will pay extra at the garden center for larger plants). Once the plants are established, climbing hydrangea tend to be vigorous growers and may need pruning in summer to keep them under control, if desired.
Landscaping Uses for Climbing Hydrangea
You can grow climbing hydrangea vines to climb up trees, garden arbors, trellises, pergolas, or fences. Because the vines become so large and heavy over time, be sure that the host structure can support the weight of the vines. The plants can also be pruned and maintained in shrub form.
Climbing hydrangea can also be used as ground covers, and they will take root where their suckers make contact with the ground. This helps the plant to spread and fill in an area, cutting down on weed growth. Some gardeners make use of the plant's white flowers in moon gardens. And because they are also salt-tolerant plants, climbing hydrangea is popular in seaside communities.
Concerns About Climbing Hydrangea on Walls
There is some debate as to whether owners of brick homes should allow climbing hydrangeas to climb up their walls (or brick chimneys). The most widely held opinion seems to be that they are safe for brick surfaces as long as the brick's mortar is in good shape.
But that does not really solve the problem. Once a mature vine has covered a brick surface, cracks can always develop in the mortar, and the vines may hide the damage or make access difficult for repairs. More generally, the problem with growing vines up a house wall is that it will eventually get into areas where you do not want it, such as gutters. Pruning can control this, but this can be difficult on a multistory home.
In terms of how vines affect the appearance of brick, there are conflicting reports as to whether the holdfasts of climbing hydrangeas will stain brick walls. In other words, staining is a possibility.
There is no debate about growing vines on surfaces other than brick: Definitely do not permit them to climb on houses sided with shingles, clapboards, or vinyl. They will cause damage to these types of surfaces.