Climbing Hydrangea can grow as both ground cover and a climbing vine.
As Ground Cover:
Mature Height: 3 to 4ft (5)
Mature Spread: up to 200sqft (5)
As a Climbing Vine:
Mature Height: 30 to 40ft (5)
Mature Spread: 5 to 6ft (5)
Newly planted climbing hydrangea have a slow growth habit that increases as they develop and become more established (5). Plants will continue to develop for 10 to 20yrs until they reach maturity (7).
Climbing hydrangea is deciduous and can grow as either a woody climbing vine or voluminous ground cover (5). Small aerial rootlets sprouting from the stem allow this woody plant to cling and climb vertical surfaces when possible, however these roots do not have much strength, so supplemental support structures are sometimes necessary to facilitate growth as a vine especially as the plant matures and increases in size (3, 5, 13). Lateral branches can grow out as much as 3 feet from main stems as climbing hydrangea becomes established and matures, adding volume to the plant and giving it a bush-like appearance (4).
The flowers grow in flat, lacy clusters called corymbs (5). Those ringing the peripheral are sterile, white, and very showy, while those toward the center are fertile and off-white (sometimes appearing greenish-yellow) (5). These corymbs bloom from May to July (usually after 3 to 5 years of growth) for about 2 or more weeks and will bloom again on old wood (4, 5, 11, 13). Unfortunately, however, flowers will only bloom on vertical stems, so climbing hydrangea cultivated as ground cover may not exhibit as many blossoms as their vine equivalents (1). Some dry the flower clusters for ornamental purposes (2, 8).
REGION OF ORIGIN
Climbing hydrangea is native to five countries in eastern Asia: Japan, Korea, China, Sakhalin (an island in eastern Siberia), and Taiwan, but is especially prevalent in Japanese woodlands and southern regions of the Korean peninsula (5, 12).
In general, climbing hydrangea is very tolerant to different habitat conditions (5, 6). Provided sufficient water is available, it can grow under a variety of light and soil conditions. Hot climates, however, generally inhibit growth (5). Consequently, climbing hydrangea propagated in the southern United States for example tend to struggle because of their intolerance to the dry heat of desert (or desert-like) regions (5). Otherwise, climbing hydrangea is very adaptable and can even be found growing naturally on trees and rock faces (5, 6).
LIGHT: Prefers full or part shade, but will grow in full sun if sufficient moisture is available or provided (5, 7)
SOIL TYPE: Grows best in soils rich in organic matter, but is otherwise fairly tolerant to different soil textures (will grow in clay, loam, or sandy soils) (7)
PH LEVEL: Neutral or slightly acidic (7)
MOISTURE CONTENT: Grows best in moist, well-drained soils (7)
PLANT HARDINESS ZONES: 4 to 8 (5)
Regular pruning is not necessary for climbing hydrangea but can be performed after flowering if necessary (4). Due to the aggressive nature of this vine, some may decide to prune several times each year to keep it confined to a specific area (2, 6). Any dead wood should be removed in early spring (4). To remove any dead or unwanted branches, prune back as far as necessary, trimming the branch just above a bud (1).