Hydrangeas are among the most striking shrubs in British gardens, admired for their large clusters of blooms that range in colour from soft pastels to vivid pinks, blues and purples. They are versatile plants that work beautifully in borders, containers or as standalone features. While they are relatively easy to grow, their care can confuse many gardeners, particularly when it comes to pruning. Knowing how to prune hydrangea plants correctly is essential for encouraging healthy growth, managing size and shape, and ensuring a spectacular display of flowers year after year. Different hydrangea species require different approaches, so understanding which type you have and when to prune it makes all the difference.
Understanding hydrangea growth habits
Hydrangeas are deciduous shrubs, meaning they lose their leaves in winter before bursting back into life in spring. The way they produce flowers varies depending on the species, and this directly affects how they should be pruned. Some hydrangeas flower on old wood, which refers to stems grown in the previous year, while others flower on new wood that grows in the current season. If you prune at the wrong time, you may inadvertently remove the stems that would have produced flowers. Recognising whether your plant flowers on old or new wood is the first step to successful pruning.
Types of hydrangeas and their pruning needs
There are several main types of hydrangeas commonly grown in the UK, each with its own pruning requirements. Hydrangea macrophylla, often known as mophead or lacecap hydrangea, is the most popular. These flower on old wood, so pruning should be minimal and focused on removing dead blooms and weak stems. Hydrangea paniculata and Hydrangea arborescens, which produce cone shaped or rounded clusters of blooms, flower on new wood. These benefit from a harder prune in late winter or early spring to encourage vigorous growth and abundant flowers. Hydrangea quercifolia, or oakleaf hydrangea, also flowers on old wood and requires light pruning. Climbing hydrangeas, such as Hydrangea anomala subsp. petiolaris, may need only light shaping and the removal of damaged stems.
When to prune hydrangeas
The timing of pruning depends on the variety of hydrangea you are growing. For mophead and lacecap hydrangeas, pruning is best carried out in spring, after the worst frosts have passed. Many gardeners leave the old flower heads on through winter, as they protect the buds beneath from frost. In spring, the dead heads can be removed by cutting back to the first pair of healthy buds. Paniculata and arborescens hydrangeas should be pruned in late winter or very early spring before new growth begins, as this encourages strong new shoots for the season’s flowers. Oakleaf hydrangeas and climbing types are pruned lightly in early spring, mainly to remove dead or weak growth.
Pruning mophead and lacecap hydrangeas
Mophead and lacecap hydrangeas are the varieties most people struggle with, as cutting too much can easily result in a season with no flowers. These types bloom on old wood, so you should avoid heavy pruning. Instead, simply cut back the faded flower heads in spring to just above a pair of strong buds. Remove any dead, weak or damaged stems completely at ground level. Every few years, you can thin out one or two of the oldest stems to rejuvenate the plant and improve airflow. This light approach maintains shape while preserving the stems that carry flower buds.
Pruning paniculata hydrangeas
Hydrangea paniculata produces dramatic, conical flower heads that are highly popular in modern gardens. Because these plants bloom on new wood, they respond well to harder pruning. In late winter or early spring, cut back each stem to about one third of its length, ideally just above a strong pair of buds. This encourages vigorous new growth and ensures the plant produces large, striking flowers later in the season. Without regular pruning, paniculata hydrangeas can become overly tall and less floriferous, so a firm annual prune is beneficial.
Pruning arborescens hydrangeas
Hydrangea arborescens, such as the variety ‘Annabelle’, produces huge, ball shaped blooms. Like paniculatas, they flower on new wood and benefit from strong pruning. In early spring, cut stems back to around twenty to thirty centimetres above ground level. This helps prevent the plant from becoming leggy and ensures robust stems that can support the weight of the large flowers. If left unpruned, arborescens hydrangeas can produce weaker, sprawling growth that collapses under the heavy blooms. Regular hard pruning keeps them compact, strong and covered in flowers.
Pruning oakleaf hydrangeas
Oakleaf hydrangeas are distinctive with their lobed leaves and cone shaped blooms. They flower on old wood, so heavy pruning should be avoided. Instead, prune only to remove spent flower heads, weak stems and any dead wood in early spring. If shaping is needed, limit cuts to just after flowering so you do not remove buds that will produce flowers the following year. Oakleaf hydrangeas are generally low maintenance, and light pruning is sufficient to keep them in good condition.
Pruning climbing hydrangeas
Climbing hydrangeas take a few years to establish but reward patience with masses of white, lace like blooms. They require little pruning apart from removing dead, damaged or overly long stems. If necessary, you can shorten shoots to control their spread, but this should be done just after flowering to avoid removing the following year’s buds. These plants often cling to walls and fences, so pruning may also involve keeping them tidy and preventing them from growing into unwanted areas.
General care after pruning
After pruning, it is important to care for your hydrangeas properly to help them recover and prepare for the season ahead. Water plants regularly during dry spells, as hydrangeas have shallow roots and dislike drying out. Mulching with compost or well rotted manure around the base helps conserve moisture, suppress weeds and improve soil fertility. Feeding with a balanced fertiliser in spring supports new growth and enhances flowering. Hydrangeas also benefit from being planted in the right soil for their type, as some species change flower colour depending on soil acidity.
Common mistakes to avoid
One of the biggest mistakes gardeners make is cutting back mophead or lacecap hydrangeas too hard, removing the stems that carry flower buds. Another error is pruning at the wrong time, particularly in autumn, which exposes fresh cuts to frost damage and sacrifices next year’s blooms. Neglecting to prune paniculata or arborescens hydrangeas can lead to sprawling, weak plants with fewer flowers. Overpruning young plants is also a common problem, as they need time to establish before heavy cutting. By understanding the type of hydrangea you have and following the correct method, these mistakes can be avoided.
Why pruning is important
Pruning hydrangeas is not just about controlling size but about encouraging healthy, balanced growth. Removing dead or weak stems improves airflow, reducing the risk of fungal diseases. Regular pruning also helps maintain a neat shape, preventing plants from becoming straggly or overgrown. Most importantly, pruning ensures a good display of flowers, as it directs the plant’s energy into producing strong shoots and abundant blooms. Well pruned hydrangeas are healthier, more attractive and longer lived, rewarding your efforts with spectacular displays year after year.
Conclusion
So, how do you prune hydrangea plants? The key lies in knowing the type of hydrangea you are growing and understanding whether it flowers on old wood or new wood. Mopheads and lacecaps require light pruning in spring to preserve their flower buds, while paniculata and arborescens varieties benefit from a harder prune to encourage new growth. Oakleaf and climbing hydrangeas need only minimal maintenance. By pruning at the right time and in the right way, you can ensure your hydrangeas remain healthy, well-shaped and covered in magnificent blooms season after season.
