Hydrangeas are the queen of the landscape with their large showy globe-shaped blooms. However, even experienced gardeners are often confused about when to prune hydrangeas. If you cut the shrub back at the wrong time then you might not get any blooms during the summer months or a lackluster display.
When to Prune Hydrangeas that Bloom on Old Growth Canes
You must wait to prune any hydrangea that blooms on old-growth wood until it has finished its flower process. A hydrangea that forms blooms on old growth starts to develop the buds during the fall months. The shrub then enters a state of dormancy until spring. Once spring arrives, the canes start to wake up and the buds again start to complete their formation cycle before flowering. The only safe window of time to prune such a shrub is right after the flowerheads are spent. If you do not heed these directions then the bush will produce very few if any flowers. In fact, some hydrangea shrubs will take two years to recover if you prune away the shrub’s old growth canes.
Pruning Hydrangeas That Bloom on New Growth
A hydrangea that blooms only on new growth needs time to develop buds on the young canes. Such varieties will not start flowering until mid-summer. However, once the blooms start to unfurl then the flowering show will continue until the first frost of autumn kills the buds. Never prune hydrangeas that bloom on new growth while it is actively flowering. Instead, cut the canes back in the late fall. Severe pruning on such varieties helps to ensure that the shrub will produce robust and vibrant blooms the following season.
Bending Canes of the Hydrangea
Remember that there is always a price to pay in removing too many of the canes to achieve a grand show. The weight of the new blooms will bend the stems of the shrub and they will plummet to the ground. Rainfall or irrigation will also lay the canes flat in the flowerbed because they are too weak to stand upright under the sheer weight. Ideally, when pruning a hydrangea that only blooms on new canes it is advised to only remove half of the plant’s canes and allow the other half to become old-growth canes that can give the shrub a healthy form. Also, when pruning back the new canes avoid chopping them off at ground level and instead cut them only to a height of 18 to 24 inches
Pruning Climbing Hydrangeas
For centuries, climbing hydrangeas have been showstoppers in old English-style cottage gardens. One of the things that has made the climber more favored is the fact that it rarely, if ever, requires pruning. Yes, all the flowers of the climbing hydrangea are produced on the old growth of the previous year, but the vine still rarely needs any pruning unless you want to control its size. Sometimes, an incredibly old vine might start to look neglected. In such a case, you can prune the vine to ground level to help rejuvenate its appearance but remember that it will not bloom for a year or two after pruning.