Hydrangea anomala subs. petiolaris (Climbing hydrangea)

It is hardy, coming as it does from eastern Siberia, northern China, Japan and South Korea where it thrives in wooded valleys, ravines and stream banks. If grown without support, it will form great mounds of stems and foliage spreading over considerable distances.

However, in the UK this shrub is most often seen not as ground cover but used to cover walls, fences or even trees. All that is needed is to plant it 30 or 40cm away from the wall where the ground is not so dry and point the stems towards the support. The plant does the rest, the new growth attaching itself to the wall or fence with aerial roots, but unlike an ivy, this does no damage and can safely be left to creep its way across the vertical surfaces, though occasionally, the weight of the plant is so great that some additional support may be a good idea. Pruning back any forward pointing growths will help to keep the plant closer to the wall and reduce chances of it falling off.

In mid to late spring the prolific white, lace cap flowers appear. The corymbs (a flower cluster whose lower stalks are proportionally longer so that the flowers form a flat or slightly convex head) consist of a mass of actual flowers that are small and greeny-white but are surrounded by prettily showy large white sterile blooms. The leaves are a mid-green, quite large, possibly up to 10cm, with serrated edges, turning a lovely buttery yellow before falling in the autumn. The woody winter framework exposes the red-tinged, soft brown exfoliating bark.

Being a woody, self-supporting climber, Hydrangea anomala subs. petiolaris can be a bit slow to start, but once it has got going it will make 30cm in all directions annually so that over 20 years it could reach 12m in height. It is happiest growing in light to full shade, so perfect for northern and eastern walls, thriving in sunnier positions only where the soil is consistently moist. In its natural habitat it grows in the shelter of woodland, so while it is quite hardy, it is best not planted in exposed situations. It prefers rich, loamy soils, (not chalk,) and will appreciate an annual mulch of compost or well-rotted manure around the roots.