Climbing Hydrangea and Climbing Hydrangea Vine
Hydrangea anomala ssp petiolaris and Schizophragma hydrangeoides
See, there's two different species that look a lot alike, have almost identical names, and are frequently mistaken for each other. (Relief is coming soon, though - the taxonomists are busy making their names more similar.) 
Climbing hydrangea/Hydrangea anomala ssp. petiolaris is hardier of the two plants - to Zone 4 or 5 - and needs some sun but likes dappled or afternoon shade, particularly in warm climates. Slow to grow in the first years, it can also take several years to begin flowering. Will grow as high as 60-80 feet into trees, though can be kept shorter. Also can be mounded as a shrub or used as a groundcover. Photo left.
Climbing hydrangea vine/Schizophragma hydrangeoides, also called "Japanese hydrangea vine," is hardier, to Zone 4. And it tolerates more shade - in fact is best in part to full shade. Doesn't have protruding woody stems like the other one, so it has a narrower, more contained habit.
- 'Moonlight', the most popular variety, has silvery leaves and is a dazzler even when not flowering. It needs a shady site. It doesn't grow as fast or bloom as vigorously as the plain species, though. Photo right.
- 'Roseum' is another popular variety, with pink blossoms. It's a faster grower and more reliable bloomer than other varieties or the plain species.
Uses
For both plants, trees and masonry walls are good hosts, also fences, tumbling over rocks. Plant young vines at the base and train new shoots so they touch the supporting surface - tape works well for this. Once attached, the new growth will attach on its own. Strong support is needed.
Details
- On both plants, flat-topped clusters of white flowers appear in early summer. In winter, the leaves drop and you see the exfoliating bark.
- Somewhat slow to grow in first years.
- Adaptable to variety of soils.
- No serious disease or insect problems for either plant.
- Native to East Asia.
Care
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Water requirements are average, meaning they need watering in moderate periods of drought.
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Late winter is the time to prune, if it's growing where you don't want it to grow. Otherwise, no pruning is required.
Photos by Missouri Botanical Garden - here, and here and here.