Plant Type and Taxonomy of Climbing Hydrangeas
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; when used as a common name for the plants, I do not capitalize the word. Technically, you could also call them climbing "hortensias" (an old common name), but relatively few people use that terminology nowadays.
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, these flower heads are reddish brown. The leaves, which are dark green in color and heart-shaped, turn yellowish in autumn (they are not grown for their fall foliage). The plants' peeling bark affords winter interest.
Planting Zones, Sun and Soil Requirements
Relatively few hardy flowering vines tolerate shade. Climbing hydrangea plants are one of them.
In fact, in hot climates, they actually prefer a location with at least partial shade. Elsewhere, they will do all right in more sunny areas, usually, if watered. Climbing hydrangeas that do get more sun tend to bloom more profusely. The soil should be moist but well-drained and contain plenty of humus.
Grow climbing hydrangea vines up trees (see below if you have concerns for the safety of your tree), garden arbors, trellises, pergolas, and fences. Because the vines become so large (and, therefore, heavy) over time, be sure that whichever support you use is sturdy. The plants can also be pruned and maintained in shrub form or used as ground covers. Make use of their white flowers in moon gardens. Their tolerance for shade gives many of us much-needed flexibility in developing our landscape designs.
Concerns About Climbing Hydrangeas: Walls, Trees
There is some debate as to whether owners of brick homes should allow climbing hydrangeas to climb up their walls (or whether homeowners should allow them to grow on chimneys). The prevailing opinion seems to be that they are safe for brick surfaces, as long as the mortar is in good shape. But therein lies the rub. After a mature vine has covered such a surface and cracks develop in the mortar, how are you going to access the mortar to repair it? The vines will be in your way. In fact, they may hide the surface so completely that you fail to detect cracked mortar altogether.
More generally, the problem with growing a vine such as climbing hydrangea upon a house wall is that it will eventually get into areas where you do not want it, such as gutters.
Sure, you can keep it pruned so as to avoid this, but do you want to be climbing high up on a ladder to execute such a task? As I get older, I know that I, for one, certainly do not want to. I am trying to reduce my landscape maintenance, not add to it.
So much for the safety issue regarding brick surfaces. In terms of how they affect the appearance of brick, I have read conflicting reports as to whether the holdfasts of climbing hydrangeas will stain brick walls. Regarding other kinds of surfaces, definitely do not permit them to climb houses sided with shakes, clapboards, or vinyl.
"Frequently concern is expressed about climbing vines that may be inundating a tree and causing irreparable damage: there has never been a proven case of damage occurring from climbing hydrangea, however," reports the Cornell Cooperative Extension, citing Richard Weir.
Climbing hydrangeas solve a problem for homeowners with shady areas to plant. Even though they will not flower as profusely if planted in full shade, these shade-tolerant vines provide you with the option of growing a plant with attractive foliage and interesting bark in areas that have too much shade for many other plants. Another nice feature is that, due to their substantial size, they can cover quite an area once they mature.
Care for Climbing Hydrangea Vines
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). As for pruning in later years, Marie Iannotti writes that once the plants are established, "they can grow quite vigorously and may need occasional summer pruning to stay in bounds."
I mentioned above that the genus name for these shade-tolerant vines is the same as the common name (in practice, if not technically): namely, Hydrangea. The Greek root hydr- refers to water, as in "hydroelectric," "hydroponics," "hydration," etc. Meanwhile, angeon comes from the Greek for "vessel." So in what way are they like a "water vessel?" Most species of hydrangea require a lot of water, thus earning the plants this watery designation.
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