Knowing if your shrub blooms on old or new wood will help you make timely cuts
Although hydrangeas do not require annual pruning, occa­sionally snipping these plants can improve their performance.
Photo/Illustration: 
Melissa Lucas

I know people are confused about how to prune hydrangeas because I get asked about it all the time. The three most common reasons for their confusion are the plant’s dead-looking appearance in winter, its failure to bloom in summer, and the reasoning that because it’s a shrub it needs to be pruned. But these popular woody plants can live long, floriferous lives without ever feeling the cold blade of a pair of Felcos. Hydrangeas, though, can handle pruning (which, if done at the wrong time, may be the cause for the lack of flowers), and sometimes you might want or need to cut them back a bit. For example, you may not like the look of the fading blooms or your shrub may be a bit too tall. Pruning hydrangeas can also improve a shrub’s vigor and increase the size of its flowers.

Not all of these shrubs should be pruned at the same time. Those that bloom on old growth should only be pruned after flowering. Others bloom on new growth and should be pruned before they wake up in spring or as they are going dormant in fall.

 

Subscribe to Fine Gardening magazine to learn more about hydrangea. In fact, you’ll find instruction and inspiration for gardeners of every skill level.

Blooms on old wood:

Bigleaf hydrangeas ( Hydrangea macrophylla cvs., USDA Hardiness Zones 6–9)
Photo/Illustration: 
Jennifer Benner
Bigleaf hydrangeas ( H. serrata cvs., Z 6–9)
Photo/Illustration: 
Courtesy of www.hydrangeasplus.com
Oakleaf hydrangeas ( H. quercifolia cvs., Z 5–9)
Photo/Illustration: 
Colleen Fitzpatrick

Prune after the flowers start to fade in late summer

To determine if your hydrangea blooms on old wood, think about when it flowers. Shrubs with this characteristic generally begin blooming in early summer and peter out by midsummer, though sporadic blooms may appear afterward. These shrubs form next year’s flower buds in late summer or early fall as the days get shorter and tem­peratures cool off. To reduce the risk of removing these buds, prune just as the flowers begin to fade. Often, the earlier you get it done after bloom, the quicker the shrub can recover, producing more and larger blooms next season.

 
Don’t prune these hydrangeas to the ground in late fall. Doing so removes all of next year’s flower buds.
Remove old blooms.
Photo/Illustration: 
Chuck Lockhart
Remove the oldest canes.

To tidy up, remove old blooms. Gardeners who want to maintain a tidy appearance can snip off spent blooms just below the flower head and remove any wayward or straggly canes at the soil line.

To improve vigor, remove the oldest canes. When a hydrangea gets old and woody, it can produce smaller blooms. Regular removal of a few of the oldest canes at the soil line can keep the shrub vigorous, producing large and abundant flowers. The same method can keep a shrub from getting too tall by targeting the tallest canes for removal.

Blooms on new wood:

Panicle hydrangeas ( H. paniculata and cvs., Z 4–8)
Photo/Illustration: 
Stephanie Fagan
Smooth hydrangeas ( H. arborescens and cvs., Z 4–9)
Photo/Illustration: 
Michelle Gervais

Cut back these shrubs in late winter before new growth begins

Because they need to grow and set buds the same year that they bloom, shrubs that flower on new wood generally start blossoming later than old-growth bloomers, beginning in midsummer and continuing until the first frost. These shrubs are forgiving if pruning is not done at a certain time as long as you avoid pruning when the flower buds are opening.

 
Photo/Illustration: 
Chuck Lockhart
To get bigger flowers, cut them all the way back.
To get bigger flowers, cut them all the way back. In late winter or early spring, these shrubs can be cut all the way back to the ground. Smooth hydrangeas will produce much larger blooms if pruned hard like this each year, but many gardeners opt for smaller blooms on sturdier stems.
Leave a framework of old growth.
Photo/Illustration: 
Chuck Lockhart
To reduce flopping, leave a framework of old growth. Some hydrangeas’ branches often fall over under the weight of their blooms, especially after overhead irrigation or after a good rain. One way to alleviate this flopping is to cut the stems to a height of 18 to 24 inches to provide a sturdy framework to support new growth.

Related Articles

To read the complete article, join now!

  • Fine Gardening eletter to help you garden smarter with timely tips and trusted advice
  • Exclusive content from the editors of Fine Gardening
  • Answers to your gardening questions from our experts
  • Access to behind the scenes videos at America's best gardens and gardening shows
  • Digital access to a library of Fine Gardening special issues and two bonus CookFresh issues from Fine Cooking - a value of over $65
  • Automatic entry into monthly giveaways from our friends and partners

Already an FGplus subscriber? Log In