Pruning Trees + Shrubs Series: Hydrangeas
As fall turns to winter and many of our trees and shrubs become dormant, it’s natural to think, “It’s time to prune!” But before you grab the clippers or pruning saw, make sure you know what you’re pruning and when it produces its flower buds.
Pruning at the wrong time can remove next season’s flowers, affect the natural shape of a tree or shrub, and sometimes create unnecessary stress for the plant. A little research before making those first cuts can make a big difference.
This is the first in a series of easy-to-follow pruning guides for some of our most popular landscape plants.
Let’s Talk Hydrangeas!
Hydrangeas brighten shady and partially shaded areas of the landscape with beautiful flowers from spring through summer and, depending on the variety, sometimes into fall. But knowing which type of Hydrangea you have is especially important before pruning.
Some Hydrangeas bloom primarily on old wood—stems that grew during the previous season—while others bloom on new wood, and newer reblooming varieties may flower on both.
Hydrangeas That Bloom on Old Wood
• Mophead Hydrangeas – Known for their large, rounded flower clusters in shades of blue, pink, purple, or white. Many traditional bigleaf Hydrangeas bloom primarily on old wood.
• Lacecap Hydrangeas – A type of bigleaf Hydrangea with flatter flower clusters featuring small fertile flowers in the center surrounded by larger showy flowers. Many traditional Lacecaps also bloom primarily on old wood.
• Oakleaf Hydrangeas – Easily recognized by their distinctive oak-shaped leaves and cone-shaped flower clusters. They bloom on old wood.
For Hydrangeas that bloom on old wood, the safest time for any necessary shaping or size-control pruning is shortly after flowering. Waiting too long into late summer, fall, or winter can mean cutting off flower buds that have already formed for the following year.
Avoid cutting old-wood Hydrangeas to the ground during winter unless you’re intentionally sacrificing the following season’s flowers or removing stems that are confirmed dead.
What About Reblooming Hydrangeas?
Newer reblooming Bigleaf Hydrangeas, including selections in series such as Endless Summer®, can produce flowers on both old and new wood. This gives them the ability to produce additional blooms from new growth even if some old flower buds are lost.
That doesn’t mean they should automatically be cut to the ground! Preserving healthy old stems can give you an earlier display of flowers, while new growth may provide additional blooms later in the season.
What About Hydrangeas That Bloom on New Wood?
Not every Hydrangea follows the old-wood rule. Panicle Hydrangeas, such as ‘Limelight’ and ‘Little Lime’, and Smooth Hydrangeas, such as ‘Annabelle’, generally bloom on new growth produced during the current season.
Because their flower buds develop on new wood, these types can generally be pruned during late winter or early spring before active new growth begins.
This is why identifying your Hydrangea before pruning is so important!
How to Prune Hydrangeas
1. Begin by removing stems that are clearly dead, damaged, or diseased. Be careful not to mistake dormant stems for dead ones during winter.
2. On an established old-wood Hydrangea that has become crowded, some of the oldest stems can be removed at the base after flowering to improve airflow and encourage fresh growth.
3. When shortening a healthy stem, make your cut just above a healthy pair of buds.
4. If your Hydrangea blooms on old wood, complete any significant shaping soon after it finishes flowering rather than waiting until fall or winter.
5. For Hydrangeas that bloom on new wood, late-winter or early-spring pruning can be used to remove weak growth and shape the plant before the new growing season begins.
Don’t Feel Like You Have to Prune!
Hydrangeas don’t necessarily need to be pruned every year. If your plant is healthy, has enough room to reach its mature size, and you’re happy with its shape, you may only need to remove dead or damaged growth and spent flowers as desired.
Tip: Consider pairing deciduous Hydrangeas with evergreen shrubs in the landscape. When the Hydrangeas lose their leaves during winter, the surrounding evergreens can continue providing structure, texture, and color.
Know Before You Cut!
The most important rule for pruning Hydrangeas is simple: know which type you have and whether it flowers on old wood, new wood, or both.
Once you know that, choosing the right time to prune becomes much easier—and you’ll be much less likely to accidentally cut away next season’s beautiful blooms!