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Why Hydrangeas don't bloom

What's keeping your hydrangea from blooming

By: Sandy Feather ©2011
Penn State Extension


Q. I planted a hydrangea in my yard many years ago. I am puzzled by the fact that some years it blooms well, but does not bloom at all in other years. Can you give me some suggestions to help it bloom every year? The hydrangea flowers are lovely and I hate to miss out on them.

A. If your hydrangea has pink or blue flowers, it is probably a bigleaf hydrangea (Hydrangea macrophylla). Although the plant itself is perfectly winter hardy in our climate, the flower buds are not. Bigleaf hydrangeas often produce a mound of foliage, but no flowers. Some hydrangeas, including bigleaf hydrangea, bloom from buds produced the previous season. This is often referred to as blooming on old wood. If those buds are killed by winter cold or removed when the plant is pruned at the wrong time of year, there will be few or no flowers the following year.


'4-Legged Factors' playing a role?

whitetail buck

Hydrangeas are also popular browse for deer, especially the flower buds, so if they commonly visit your yard, they may be the culprits. If you find it necessary to prune your hydrangea, do so as soon as it finishes blooming because it starts setting next year’s flower buds soon after.

'Glowing Embers' Hydrangea
Hydrangea macrophylla
'Glowing Embers'

Of course, you often see bigleaf hydrangeas blooming locally. That is common after a very mild winter, or if they are planted in a protected location. They also occasionally bloom from flower buds produced during the current growing season (“blooming on new wood”). As a matter of fact, plant breeders have exploited this tendency in order to produce bigleaf hydrangeas that bloom reliably for gardeners in colder climate. Known as the Endless Summer® Collection, they include the mophead forms Endless Summer® and ‘Blushing Bride’ as well as a lacecap form called Twist-and-Shout™.

 


Hardy Sorts of Hydrangeas

Other hydrangeas that are completely hardy for us include a vine, climbing hydrangea (Hydrangea anomala subspecies petiolaris); and the following shrubs: smooth hydrangea (Hydrangea arborescens); panicle hydrangea (Hydrangea paniculata); and oakleaf hydrangea (Hydrangea quercifolia). All typically have white flowers, although a new smooth hydrangea called Bella Anna™ has been introduced that sports pink flowers.

Tardiva Hydrangea
Hydrangea paniculata 'Tardiva'
Tardiva Panicled Hydrangea

Smooth hydrangea and panicle hydrangea shrubs bloom on new wood. They can be pruned in late winter or early spring when necessary. Oakleaf hydrangeas flower on old wood and are best pruned as soon as they finish blooming.

Climbing hydrangeas do not require much pruning, only to retain their shape. They are slow to get started, but can climb to 50 - 60 feet. Be sure to provide adequate support for them, such as a sturdy wall, fence or building. They climb by aerial rootlets, much like English Ivy (Hedera helix).

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