Hydrangeas are the rockstars of summer gardens, but with uncontrolled growth, these perennials can become unruly. Knowing when to prune hydrangeas is important if you wish to maximize your blooms each season.
Unfortunately, there is no one-size-fits-all answer for when to prune this summer shrub. However, if you know what type of hydrangea you are growing, you are halfway there!
Continue reading to learn about the main types of hydrangeas and discover when it is time to give your plant a haircut.
When to prune hydrangeas
Hydrangeas come in several types, with differing bloom times, flower types, and pruning needs. Since pruning time depends on which type of wood your blooms grow on, it can be difficult to decide when the best time to prune hydrangeas is.
Some types of hydrangeas form their flower buds on old wood, and some form them on new wood. And, to make things even more confusing, Endless Summer Hydrangea, the variety I grow, forms flower buds on both old and new wood!
If you prune at the wrong time, you can significantly limit the number of flowers you will have this year.
Old wood vs new wood
“Old wood” refers to the previous year’s growth on a hydrangea shrub, while “new wood” refers to the current year’s growth. Old wood has a greyish color, and new wood is much more greenish.
Old wood is also somewhat brittle, while new wood is softer and more pliable.
If you prune old wood hydrangeas in late fall, winter, or early spring, you will remove their flower buds, leaving you with a plant that won’t give you many blooms this year. Instead, prune this type in early fall after the flowers have faded.
Pruning this variety of hydrangea in fall gives it plenty of time to develop wood that will be “old” when the next season’s flower buds emerge.
With new wood hydrangeas, you have more flexibility since they form flower buds in spring on this year’s growth. Prune this type in late fall or early winter, once the plant is dormant, or wait till early spring when the new growth starts.
Hydrangea types and when to prune them
A common question that I get from readers is “Should hydrangeas be pruned in fall?” Now that we know there is a reason for pruning at both fall and spring (it’s all about the blooms!), let’s examine the specific types of hydrangeas and learn the best times to prune them.
Bigleaf hydrangeas
Bigleaf hydrangeas (Hydrangea macrophylla) have large, showy flowers, and lush foliage with dark, glossy leaves. Their flowers are described as mopheads or lacecaps.
This type of hydrangea loses its leaves in winter and regrows in spring.
Pruning time for bigleaf hydrangeas is critical to ensure the maximum number of flowers. They bloom on old wood and should be pruned in early fall after the flowers have faded.
Smooth hydrangeas
Smooth Hydrangea (Hydrangea arborescens) is also called wild hydrangea. This type of hydrangea has large, rounded clusters of flowers called corymbs.
The blooms are usually a creamy white and the leaves are large, oval, and serrated on the edges. Bloom time is spring and early summer.
Smooth hydrangea blooms on new growth. This gives some flexibility with pruning time.
Pruning can be done in late winter or early spring to encourage vigorous flowering.
Mountain hydrangeas
Mountain hydrangeas (Hydrangea serrata) produce flattened flower clusters called corymbs or panicles. The flower color ranges from pink and blue to white.
Leaves of mountain hydrangeas have serrated edges. This type of hydrangea has a compact growth habit suited to smaller gardens.
Hydrangea serrata blooms in late spring through early summer on both old and new wood. This means that little pruning is necessary.
If you decide to prune, you can do it after flowering in the fall or when growth appears in early spring. Deadheading faded flowers will keep the plant tidy.
Oakleaf hydrangeas
As the name would suggest, oakleaf hydrangeas (Hydrangea quercifolia) have deeply-lobed leaves that look like those of oak trees.
Their flowers, which bloom in late spring to early summer, are cone-shaped and are originally cream or green in color, and then gradually become pink, rose, or even deep purple, depending on the cultivar.
Oakleaf hydrangea produces stunning cone-shaped clusters of flowers that emerge in late spring to early summer. They are generally low-maintenance once established in your garden.
This type of hydrangea flowers on old wood. Pruning should be done immediately after flowering to avoid removing next year’s flower buds.
Panicle hydrangea
Panicle hydrangea (Hydrangea paniculata) produces large, showy cone-shaped flowers called panicles. These panicles can range in size from 6 to 18 inches long. The flowers start creamy white, and as they mature, they gradually transition to shades of pink, red, or even bronze, depending on the variety grown.
Unlike some other hydrangea species, the color of panicle hydrangea flowers is not influenced by soil pH.
Panicle hydrangeas bloom on new wood (this season’s growth.) This makes them less susceptible to winter damage and ensures that flowering is dependable. Bloom time is typically from mid-summer to early fall, which is longer than other species of hydrangeas.
Prune panicle hydrangeas in late winter or early spring before new growth starts.
Climbing hydrangeas
Climbing hydrangea (hydrangea anomala subsp. petiolaris) is a deciduous woody vine that can climb and cover walls, fences, and arbors. It has large, flattened clusters of creamy white flowers called corymbs.
The flowers can reach up to 10 inches in diameter and emerge in late spring to early summer. The blooms are very fragrant and attract pollinators such as bees and butterflies.
Climbing hydrangea blooms on old wood, so you should prune it after flowering finishes, before new buds form.
Tips for pruning hydrangeas that bloom on old wood
While it is true that hydrangeas that bloom on old wood should be pruned in the fall after flowering, you may still want to do some maintenance pruning in early spring.
I use this as a time to remove the oldest canes or those that cross each other. This gives me a neater shrub.
Note that you will be removing some formed buds and will lose those flowers this year, but it’s worth it to me to keep my hydrangea bushes in a more manageable size.
When to prune reblooming hydrangeas
Some types of hydrangeas are rebloomers. This means they can produce flowers on both old and new wood throughout the growing season.
These include certain varieties of Hydrangea macrophylla (e.g., Endless Summer), Hydrangea serrata, and Hydrangea arborescens (e.g., Invincibelle series). Since they can bloom on both types of wood, the best time to prune them often depends on your desired pruning goals.
Here are some guidelines for when to prune reblooming hydrangeas:
- If all you want to do is shape or tidy up your shrub, light pruning can be done any time.
- For more significant pruning to control the plant’s size, late winter to early spring, before new growth begins, is the best time to tackle this job.
- To encourage continuous blooming throughout the growing season, you can deadhead spent flowers regularly as they fade.
- Since reblooming hydrangeas may produce flowers on both old and new wood, it’s best to avoid heavy pruning (renewal pruning) in late summer or fall, as this could potentially remove next year’s flower buds.
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When To Prune Back Hydrangeas by Type - Printable
Hydrangeas have showy blooms and are garden stars, but they can get untidy if not pruned. But when do you do this job?
It depends on how your hydrangeas set blooms - on old wood or new wood (this year's growth.)
If you prune at the wrong time, you will sacrifice your flowers.
Print out the list and keep it for reference in your garden journal.
Materials
- Heavy card stock or printer paper
Tools
- Computer printer
Instructions
- Load your printer with heavy card stock or printer paper.
- Choose portrait layout and if possible "fit to page" in your settings.
- Take the shopping list with you the next time you go plant shopping.
Notes
Using this print function on this card will print a calendar that fills about 3/4 of an 8 x 11 sheet of paper.
To fill the entire page, choose "fit to page" on your printer if you have this setting, or use the link in the post above and print using the browser print feature
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