How to prune a hydrangea in spring

Pruning prevents hydrangeas becoming woody and congested, and channels the plant's energy into producing strong growth and large blooms. After pruning, mulch the plant with well rotted manure or compost, which will help it to grow back strongly.

Different types of hydrangea are pruned in different ways, as some flower on old wood and some on new. Pruning incorrectly will affect flowering. Hydrangea macrophylla, Hydrangea aspera, Hydrangea serrata and Hydrangea quercifolia are lightly pruned by cutting back the old flower heads to a pair of strong emerging buds below. Hydrangea paniculata and Hydrangea arborescens can be cut back harder, and will generally flower better if pruned in this way.

If you're not sure which type of hydrangea you have, it's best just to deadhead it and observe how it grows. If you notice that it produces flowers on this year's growth, you can prune it harder next year. Hydrangea paniculata has quite a different appearance to most others, with flame-like, pointed flower heads.

Find out more about how to grow hydrangeas, and if you'd like to grow more hydrangeas in your garden, be inspired by our pick of nine of the best hydrangeas to grow.

Pruning hydrangeas: jump links

• Pruning mophead and lacecap hydrangeas
• Pruning Hydrangea serrata, H. aspera and H. quercifolia
• Pruning Hydrangea paniculata and Hydrangea arborescens

Mophead and lacecap hydrangeas

Mophead and lacecap hydrangeas (Hydrangea macrophylla) flower on the previous years' growth. They are an exception to the rule that says shrubs that produce their flowers on the previous season's growth should be pruned after flowering.

The structure of hydrangea stems means that it's best to leave cutting back until spring. This is because the stems are cork-like, rather than woody, and hold enough moisture inside them during winter for this to freeze in frosty weather. If they are pruned in autumn or winter, the buds are exposed to the worst of winter weather and can freeze, killing the stems and their buds.

Leaving the old flowers on the plant over winter, until the worst frosts are over, will help protect the stems and their new buds. Once the sap starts to rise in spring, these buds will open and many should go on to carry blooms.

Remove last year's flower heads

In April, remove old flower heads to just above a pair of strong emerging buds on a section of reasonably thick stem. Hydrangea buds can be easily knocked off, so cut carefully using the tips of your secateurs.

Cut out thin, weak and congested stems

Cut out any thin, weak stems around the base of the plant and remove a few of the largest, oldest stems from as low down as possible to promote new shoots from the base and avoid a build up of old wood.

If you have an overgrown plant that is becoming very dense, cut some of the stems at the centre of the shrub right to the base. This opens up the structure and lets in more light and air.

Hydrangea aspera and Hydrangea serrata

Hydrangea aspera, Hydrangea serrata and Hydrangea quercifolia are also lightly pruned in spring – just remove old flower heads and old, crossing or over-long stems in a similar way to mopheads and lacecaps. Cut down to a strong bud on a section of reasonably thick stem.

Hydrangea paniculata and Hydrangea arborescens

Hydrangea paniculata and Hydrangea arborescens produce flowers on new wood, which means that you can cut them back harder without losing this year’s flowers. Pruning is not essential, but left unpruned the plant will get taller, with most of the flowers at the top. By cutting them down to a low framework each year you will encourage more flowers, and in a place where they can be seen. Just be sure to mulch them well afterwards to help them grow back strongly. Watch our expert guide to pruning Hydrangea arborescens 'Annabelle'.

Cut back to a healthy framework

Cut back in mid spring, pruning last year’s growth back to a healthy framework between 30cm and 60cm high. Prune to just above a pair of healthy buds on each stem. Cut back to the lowest healthy buds for big flowers or less hard for a natural look or a taller plant.

Pruning climbing hydrangeas

Climbing hydrangeas such as Hydrangea anomola subsp. petiolaris and Hydrangea seemannii should not be pruned until after they have flowered, in summer. Cut back any straggly shoots but avoid cutting too much back at the top of the plant, as most flowers are produced here. Hard pruning of established plants can be done in the spring, but be aware that this can impact flowering. If an established plant is overgrown, prune it back over a few years to avoid shocking the plant and encouraging lots of weak stems to grow in response.

Common issues when pruning

The main issues when pruning hydrangeas are:

• Pruning at the wrong time of year – check the type of hydrangea you have before pruning. They all have individual needs – see above for how to prune the different types. Pruning in winter can lead to frosted stems.
• No flowers – pruning a hydrangea that flowers on old wood too vigorously or at the wrong time of year can lead to a lack of flowers
• Overgrown shrub – a lack of regular pruning can lead to an overgrown hydrangea, which will then need a hard prune. Hard pruning can reduce flowering so it’s better to keep on top of annual pruning

Frequently asked questions

What is the best month to prune hydrangeas?
The best month to prune most hydrangeas is between March and April, but climbing hydrangeas should be pruned after flowering, in August or September.

Do hydrangeas need to be cut back for winter?
No. Pruning in autumn or winter will expose next year's flower buds to cold air and rainfall, making them much more likely to be damaged by winter frosts. Leave the flower heads from last year in place to form a protective blanket over these buds, then prune in mid-to-late spring.

What month do you deadhead hydrangeas?
It’s better to leave the flower heads on hydrangeas over winter. Lacecap hydrangeas are hardier than mophead types and can be deadheaded after flowering, but it would be best to do this no later than August, cutting back to just above a pair of leaves. This will give any new growth encouraged by pruning enough time to mature and toughen up ahead of winter frosts.

Can hydrangeas be cut back hard?
Cutting hydrangeas back hard will affect the amount of flowers it has the following year, for those types that flower on old wood, but it may be the best course of action if the plant is very overgrown. In this case, you can cut all stems to the base and then follow up with a replenishing mulch to encourage new stems to grow, but these will not produce flowers until the following year. Prune and thin out these new stems somewhat the following spring, to help create a reasonably open, compact shrub. Alternatively, prune out a few of the oldest, toughest stems annually, cutting right down to the base, to rejuvenate the shrub over a few years. Climbing hydrangea can also be cut back hard in the spring, but this will affect its flowering.