Hydrangeas! I love them. These wonderful plants dazzle me with beautiful blooms and lush foliage. Some of the newer cultivars have interesting bark, gorgeous fall leaf color and stunning reddish or purplish leaves in the growing season. The variety of cultivars available now is definitely dizzying. I want them all! But despite all the new cultivars, my favorite (at the moment) is the lacecap, with Pee Gee running a close second.
Hydrangeas are easy to grow, but pruning is another matter. You must know which type of hydrangea you have, or you won’t know when to prune it. If you lop at the wrong time, you’ll never see blooms, and that would be a tragedy.
Climbing hydrangeas (anomala), Hills of Snow hydrangea (arborescens) and Pee Gee hydrangea (paniculata) bloom on the current season’s growth. They can be pruned in late winter or early spring, since their flower buds develop on new growth.
Bigleaf hydrangeas (Hydrangea macrophylla and serrata cultivars—which includes the mopheads and lacecaps) bloom on last year’s new growth--also known as old wood. Prune dead wood in early spring, but NEVER prune last year’s new growth or your prize plant will be bloomless. If you’d like to shape your bigleaf hydrangea with a little pruning, the only time that’s safe to do so is in summer, immediately after it has finished blooming.
By the way, there’s a difference between old wood and dead wood. Check for dead wood by gently scraping your pruning tool on the surface of the woody stem. If you see green underneath, the stem’s alive and should not be pruned.
And there’s one more general pruning rule to heed. Do not prune any hydrangea in late summer or early fall. Pruning at this time may encourage late growth that may not harden off for the winter.
Just to confuse us completely, one of the newer cultivars, Endless Summer, blooms on both old and new wood. When to prune that one is anybody’s guess. If all this pruning information is making you crazy, try the new macrophylla cultivar called Cityline that never needs pruning. Or just don’t prune at all.
New hydrangea cultivars are coming to market every year. And those plant breeders are not even close to finished. New trends in cultivars include re-bloomers, plants that bloom on new wood, and small patio hydrangeas.
Are you a hydrangea lover too? Want more info? I’d recommend Michael Dirr’s book, Hydrangeas for American Gardens. Or go to Hydrangea Care.
Do you have a gardening question? In Delaware County, call our Master Gardeners hortline at 610-690-2671 on Tuesdays and Thursdays from 9 AM-12 NOON.
UPCOMING MASTER GARDENERS EVENTS
November 10, 2007: Thanksgiving & Fall Flower Arrangement
We'll present great ideas for fall flower arrangements. Learn techniques to make your own one of a kind creation, whether in a pumpkin, bowl or basket. This is a hands-on workshop. Bring hand clippers or scissors. We supply the rest.
Registration required for all events. Please call 610-690-2655 for more information or visit our website
