Hydrangeas make beautiful focal points in the garden, and they generally require minimal care other than pruning. Although many hydrangeas have interesting foliage and bark, most are grown for their large, showy blossoms. If hydrangeas don’t bloom for a season, it's usually due to one of three reasons: They didn't get enough sun, an early frost or cold spell killed the buds, or they were pruned at the wrong time. How and when you prune hydrangeas depends on which type you have.
Equipment / Tools
- Bypass pruners
Bigleaf Hydrangea (Hydrangea macrophylla)
The bigleaf hydrangea often has flowers whose color changes with the soil pH: blue in acid soil and pink in alkaline soil. However, there are also a few varieties that simply stay white. Its leaves are coarsely serrated and glossy, dark green. Bigleaf hydrangeas set their flower buds from late summer to early fall. Thus, pruning in the spring or even late fall will remove the flower buds and any chance of getting blooms for that season.
Spent flowers can be trimmed away as they fade to keep the plant looking tidy. When most of the flowers have faded, it's time for pruning. Selectively prune the dead and weaker stems, both old and new, using bypass pruners. But don’t prune all the old wood because this is what will keep flowering as the new growth matures.
Bigleaf hydrangeas are the variety most susceptible to winter bud injury. If you live in an area with severe winters, you might need to offer it some protection. Tying the branches together and wrapping them with burlap can help the plant survive winter. Remove the burlap when the buds begin to swell.
Smooth Hydrangea (H. arborescens)
Smooth hydrangea, including the popular cultivar H. arborescens 'Grandiflora,' doesn't usually have any problems blooming, though its white flowers aren't as showy as we normally expect from hydrangeas. It's a round shrub with leaves that are somewhat rounded with a pointed end, paler on the underside than on the top.
This shrub blooms on new wood. So pruning should be done in early spring to ensure plenty of growth for flowers. Remove any branches that have been injured or killed over the winter, and lightly trim others to shape the plant.
Peegee Hydrangea (H. paniculata 'Grandiflora')
This is the most common hydrangea variety. Also known as panicle hydrangeas, peegees display massive snowball-shaped flower clusters in mid- to late summer. The flowers start out white and slowly turn pink, drying and remaining on the plant long after the leaves have fallen.
Flower buds occur on new spring growth. Some light pruning of individual stems in late winter or early spring not only will keep the plant from becoming overgrown but also will encourage healthy growth and flowers. During the growing season, you can deadhead the flowers (remove spent flowers) and clean up the overall shape of the plant as soon as the flowers become unattractive.
Oakleaf Hydrangeas (H. quercifolia)
It's probably not surprising that oakleaf hydrangea is easily recognized by its oak leaf-shaped foliage. Because its major attraction is the foliage, any loss of blooms is less disappointing than in most other hydrangea varieties.
Oakleaf hydrangea blooms on old growth and should be pruned immediately after it has finished flowering. If it has experienced winter dieback, prune the stems back to below the point of injury.
Mountain Hydrangea (H. serrata)
Mountain hydrangeas are small flowering shrubs with narrow, pointed leaves and flattened flower heads. This plant is sometimes confused with Hydrangea macrophylla because of their similar flowers. However, this type doesn't have the big leaves of Hydrangea macrophylla.
Blooming occurs on old wood, and the plant's pruning needs are minimal. Prune after it flowers, trimming back flowering stems to a pair of healthy buds. In early spring, prune unhealthy stems to ground level.
Climbing Hydrangea (H. anomala petiolaris)
The stunning climbing hydrangea is the type you see slowly making its way up a tree or other support. It's a vine not a shrub, and it generally requires little to no pruning. This plant flowers on old wood grown during the previous season.
Once climbing hydrangeas become established, they can grow quite vigorously and might need occasional late winter pruning to set boundaries for the coming season. Neglected, overgrown vines can be cut back to ground level in early spring to rejuvenate the plant.
|When to Prune Different Types of Hydrangeas|
|Category||Blooms on old or new wood||When to prune|
|Bigleaf hydrangea||Old||Immediately after flowers fade|
|Smooth hydrangea||New||Late winter or early spring before new growth starts|
|Peegee hydrangea||New||Light pruning in late winter or early spring|
|Oakleaf hydrangea||Old||Summer after flowers fade|
|Mountain hydrangea||Old||Immediately after flowering|
|Climbing hydrangea||Old||Winter or early spring, only when necessary to control size|
Tips for Pruning Hydrangeas
In general, varieties that bloom on old wood should be pruned immediately after they flower. And those that bloom on new wood should be pruned before new growth begins in spring.
Always remove dead, damaged, or diseased stems as the first step during routine pruning. When shortening stems, cut back to just above a pair of healthy buds. Winter-damaged stems can be cut back to living wood.
Guide to Pruning Hydrangeas. University of Maryland Extension