Everything You Need to Know About When and How to Cut Back Hydrangeas Each Year
Hydrangeas are some of the most popular flowers in the world. These beautiful deciduous shrubs and trees produce a gorgeous array of colors, including white, pink, purple, or blue flower heads and dark green serrated foliage. Hydrangeas flowers also carry lots of beautiful meanings and symbolism. While cutting back these stunning plants seems like a shame, it can have benefits. In this guide, we’ll take you through why, when, and how to cut back hydrangeas.
- When Do You Cut Back Hydrangeas – The Essentials
- Is Pruning & Deadheading Hydrangeas Necessary?
- Key Considerations When Cutting Back Hydrangeas
- When to Cut Back Hydrangeas
- How to Prune Hydrangeas
- When to Cut Back Hydrangeas – The Final Word
When Do You Cut Back Hydrangeas – The Essentials
The best time for pruning hydrangeas depends on the type of hydrangea you have. Most hydrangeas should be pruned either after they finish flowering or in late winter/early spring before new growth starts. Most hydrangeas flower on old growth, so cutting them back hard isn’t advised.
Is Pruning & Deadheading Hydrangeas Necessary?
Pruning and deadheading hydrangeas aren’t strictly necessary, and these deciduous perennials will still live healthy lives without being cut back. However, pruning hydrangeas at the right time helps prolong flowering and encourages strong growth next season. Most hydrangeas only require light pruning to remove old flower heads and damaged or diseased stems.
Key Considerations When Cutting Back Hydrangeas
The primary consideration to keep in mind when cutting back hydrangeas is whether the plant flowers on old or new growth. Hydrangeas that flower on old growth cannot be trimmed too vigorously, or they will struggle to produce new flowers. These hydrangeas are usually pruned once the flowering season has finished.
Hydrangeas that flower on new growth respond better to being cut back hard. This allows the plant to focus all its resources on producing new growth and bigger flowers next season. Hydrangeas that flower on new growth should be pruned or cut back in late winter or early spring.
It’s also vital to use clean tools when pruning or cutting back hydrangeas. Cutting into any plant creates the risk of spreading diseases between plants or providing an opportunity for pests. Before you start pruning, use a 5% bleach solution to clean your tools.
If you’re trimming a hydrangea, avoid removing too much of the plant in one go. Cutting off too many stems can shock the plant and cause immense damage. Never cut off more than a quarter or a third of your hydrangea plant.
When to Cut Back Hydrangeas
The beauty of hydrangeas is that there’s a type of hydrangea to suit any space (plus, they’re also easy to divide and propagate). But not all hydrangeas should be pruned at the same time. Let’s go through the most popular types of hydrangeas and when it’s best to prune them.
Bigleaf & Lacecap Hydrangeas
Bigleaf hydrangeas (Hydrangea macrophylla), also known as lacecap hydrangeas, are one of the most well-known varieties. These hydrangeas are famous for their large round flower heads that come in colors like white, pink, and purple. These flowers can bloom throughout the summer and will benefit from a couple of rounds of fertilizer for optimal growth.
Bigleaf hydrangeas flower on old growth, so don’t cut them back hard. Once flowering has finished in late summer or fall, prune the stems back to a healthy, unopened set of buds. In late winter or early spring, remove any damaged or weak stems.
Climbing hydrangeas (Hydrangea petiolaris or Hydrangea anomala) are the biggest variety of hydrangea. These sprawling perennials use aerial roots to climb up walls, trellises, or even trees. Climbing hydrangeas are prized for their large clusters of fragrant white flowers that can reach almost 8 inches wide.
Climbing hydrangeas require the least pruning of the common hydrangea types. These impressive plants are usually pruned to control their size and keep them contained. Climbing hydrangeas flower on old growth, so trim them once the flowers finish in early summer.
Mountain hydrangeas (Hydrangea serrata) are small hydrangeas that usually don’t grow larger than 4 ft. These hydrangeas produce lovely pink, purple, or even blue flowers from early to late summer. Mountain hydrangeas are ideal for smaller gardens and also do well as container plants.
Mountain hydrangeas flower on old growth and only need light pruning. Although these hydrangeas are pretty hardy, cutting them back too much will damage them. Prune mountain hydrangeas once they finish flowering (also a good time to transplant hydrangeas if needed), with a second pruning in late winter/early spring to remove damaged stems.
Oakleaf hydrangeas (Hydrangea quercifolia) have dark green lobed leaves similar to the foliage of oak trees. Oakleaf hydrangeas are native to the United States and grow as small upright trees. These hydrangeas have gorgeous white flowers that fade to pink as the flowering season progresses.
Oakleaf hydrangeas flower on old growth, so it shouldn’t be cut back too hard. Prune oakleaf hydrangeas once the flowers have finished in the fall. This allows the stems to develop into healthy old wood before the next growing season.
Panicle hydrangeas (Hydrangea paniculata) are native to eastern parts of Asia. Panicle hydrangeas produce cone-like flower spikes rather than round flower heads. The flowers fade from white to pink, with the flowering season running from mid-summer into fall.
Panicle hydrangeas produce their flowers from new growth. This means that they can be cut back somewhat hard in late winter or early spring before the next growing season. Being cut back like this encourages lots of new growth to form, producing a bigger bounty of flowers.
Smooth hydrangeas (Hydrangea arborescens) are another hydrangea variety native to North America. In early summer, smooth hydrangeas produce rounded flower heads with light green flowers. As the flowering season rolls into fall, the flowers gradually turn creamy-white.
Smooth hydrangeas flower on new growth and can benefit from being cut back fairly hard. In warmer climates, smooth hydrangeas can be cut back almost to the ground in late winter or early spring. The harder they are cut back, the bigger flowers they produce in the following season.
How to Prune Hydrangeas
The three main methods of trimming hydrangeas are deadheading, pruning, and cutting back. Each method is used at different times for different reasons. Some hydrangeas respond better to specific methods than others, so let’s look at each practice in more detail.
It’s worth noting that hydrangeas are considered toxic, so it’s prudent to wear a pair of gardening gloves throughout the process.
While it isn’t strictly necessary, deadheading (removing spent flowers) can tidy up your hydrangea. Removing spent flowers also encourages fresh blooms to come through, prolonging the flowering season.
However, as the end of fall approaches, it’s a good idea to stop deadheading. If your hydrangea blooms on old growth, leaving faded flower heads on the plant helps protect the stems during the winter. This also prolongs the interest of your hydrangea throughout the winter months.
Pruning usually involves selectively cutting off stems to reduce a plant’s size or remove weak or damaged branches. Most types of hydrangeas will only need to be pruned once or twice each year. Varieties that flower on old growth should be pruned right after their flowering season has ended.
When pruning a hydrangea, always cut just above a healthy set of buds. This will allow the stem to regrow and produce new flowers next season.
Cutting back is usually more drastic than pruning. Most hydrangeas will suffer badly if cut back too harshly. Varieties that flower on new wood, like panicle hydrangeas and smooth hydrangeas, benefit most from cutting back
Cutting back these hydrangeas in late winter or early spring enables to plant to concentrate on fresh new growth. If done correctly, this can result in bigger, more numerous blooms.
When to Cut Back Hydrangeas – The Final Word
Pruning hydrangeas can keep them looking fabulous throughout the flowering season, so you can enjoy these beneficial plants for longer. But different types of hydrangeas need to be pruned differently. Hydrangeas that flower on old wood should be cut back after flowering. Hydrangeas that flower on new growth should be pruned in late winter or early spring. For more, see our essential guide to growing hydrangeas for beginners.
Edd is a budding content writer and gardener living in the United Kingdom. He has a bachelor's degree in Creative and Professional Writing and has written for several gardening publications online. He is passionate about nature and sustainability with a focus on gardening and wildlife.