It is important to know how to prune hydrangeas to get the best out of these spectacular shrubs. Once considered a little unfashionable, hydrangeas have experienced a revival in popularity in recent years, appreciated for their range of colourful and showy blooms – some of which are also wonderful when dried for enduring floral displays in the home.
With their large, clustered flower heads, hydrangeas make a striking addition to garden borders or containers, and pruning is an important aspect of learning how to grow hydrangeas successfully, too
When pruning hydrangeas, it is important to be aware that not all varieties are pruned in the same way, and different types require a slightly different approach.
How to prune hydrangeas – for beginners
Hydrangeas are generally pretty low maintenance shrubs, and once you have identified the variety that you have in your garden, it's easy to get to grips with how to prune them.
Some hydrangeas flower on old wood and some on new wood, so it is important to prune them the correct way so as to not detrimentally affect their flowering.
Pruning hydrangeas will help the formation of new flowers and promote good shape
When should hydrangeas be pruned?
'Apart from climbing hydrangeas, which are pruned in summer, most hydrangeas are pruned in early spring
Although many hydrangeas are pruned at the same time of year in early spring, the way you prune the different varieties differs.
Pruning mophead hydrangeas and lacecaps
The method for pruning mophead hydrangeas and lacecap hydrangeas (Hydrangea macrophylla) – also known as bigleaf hydrangeas – is the same.
Mophead hydrangeas are a common choice for gardens with their full, roundish heads of large petals in shades of blue, pink, green and white. This makes them a popular shrub choice for cottage garden ideas.
Lacecap hydrangeas are identified by tiny flowers in the center of the bloom and an outer border of larger petals.
These varieties should be pruned in early spring.
'It’s best to leave the faded blooms in place over the winter to protect tender new buds from frost damage
When pruning mophead hydrangeas and lacecaps in early spring
Cut out one or two of the oldest, weakest stems at the base of the plant to encourage new growth that will have better blooms.
Using secateurs, carefully remove old flowerheads just above a pair of buds.
Be careful not to cut off any of the flower buds.
If the bigleaf hydrangea shrub has been neglected and has lots of overlapping, tangled branches, you can do a harder prune and cut the stems down to the base of the plant. However the hydrangea will then not bloom until the following year.
How to prune climbing hydrangeas
Climbing hydrangeas, such as Hydrangea anomola subsp. petiolaris, Hydrangea seemannii or H. serratifolia are pruned in summer, after flowering. The reason that climbing hydrangeas are pruned in summer is because the flowers are produced on the previous year's wood. If they are pruned earlier in spring, before flowering, the blooms for that year will be sacrificed.
Prune Hydrangea petiolaris immediately after flowering to shorten any branches growing out from the wall or support, otherwise only light pruning is required to remove dead or damaged stems,
Most flowers appear at the top of climbing hydrangea plants, so the RHS advise to leave as much of this unpruned as possible.
How to prune Hydrangea paniculata and Hydrangea arborescens
Hydrangea Paniculata with its cone-like heads of blooms, and Hydrangea aborescens with its spherical flower heads, are also pruned in early spring.
They produce flowers on new wood, so they can be pruned back harder without sacrificing that year's flowers.
Prune old branches back to the lowest pair of healthy buds near ground level for a neat framework.
'By cutting stems to different heights, you’ll get flowerheads produced at different levels,
Other types of hydrangea, including Hydrangea aspera and Hydrangea quercifolia, need only light pruning in spring. Simply remove dead flower heads and overlong or crossing stems.
What happens if you don't prune hydrangeas?
If you don't prune hydrangeas then they can eventually resemble a tangled mass of woody stems, and the flowers will become smaller and less showy.
Regular pruning of hydrangeas helps to maintain their shape and also encourages new growth and a better display of blooms.
It's this strong, new growth that ensures you have lots of large, healthy flowers to enjoy in the years to come,
Do you cut off dead hydrangea blooms?
Deadheading hydrangeas – or removing spent flowers from the stem to encourage better blooming later on – can be done with some hydrangeas but not all.
The RHS recommends that dead blooms should only be removed from mophead hydrangeas after flowering in mild areas. Their advice is that it is better to leave the flowerheads on the plant over winter to provide some frost protection.