Prune climbing hydrangea only after flowering
Q: We planted a climbing hydrangea about four years ago. It has not yet bloomed. What I have read about them is “first they sleep, then they creep, then they run.” It did all these over the years and last summer it really grew. Is there something that I can feed the plant to encourage the bloomâ¢ Is there anything else that the plant would need to produce bloomsâ¢ It receives afternoon sun, well-drained soil, and it is trained up a trellis.
A : Climbing hydrangea, Hydrangea anomala petiolaris , is a native of Asia and is a true climbing vine. Aerial roots produced along the stems allow the plant to cling to fences, arbors, trellises, buildings, and even trees. At maturity, climbing hydrangeas can reach 30 to 50 feet high and 5 to 6 feet wide. Or, if you don’t have a sturdy place for it to climb, this hydrangea makes a beautiful groundcover with a single plant eventually blanketing a 10 foot by 10 foot area.
The leaves of climbing hydrangeas are glossy green and heart shaped and, though this vine is deciduous, the plant is lovely even in the dead of winter due to its cinnamon-colored bark. Climbing hydrangea will tolerate full shade but partial sun is best; the north or east side of a building, or the dappled shade of a tree canopy, are its favorite places.
The large, flat, lace-cap flowers are creamy white and appear in early summer. They are notorious for taking their time to arrive, with a normal first appearance being five to six years after planting. They are worth the wait, though, because once they do decide to show up, there’s no stopping them and the plant will be smothered in beautiful blossoms more years than not.
The flowers are formed on year-old wood, meaning the growth that occurs this year will produce next summer’s flowers. This means that any pruning you do needs to take place immediately after the plant flowers, in early summer. Pruning in spring, fall or winter removes potential flower buds.
Climbing hydrangea prefer fertile, well-drained but moist soil. Though fertilizing will not make it bloom any faster (only maturity can do that), an annual application of a balanced organic granular fertilizer isn’t a bad idea. Go on the light side, though, as over application can cause too much unsupported growth.
A new variety has recently entered the market and is worth seeking out if you are looking to add to your collection. “Firefly” climbing hydrangea has unique variegated foliage — dark green leaves with a broad creamy yellow margin — that makes a stunning backdrop for its creamy white flowers. “Miranda” is another beautifully variegated selection.