How to Grow Hydrangeas

Hydrangeas are a popular shrub with distinctive large flowerheads that thrive in the UK's temperate climate. The flowers vary in size, colour and shape, meaning they can look at home in various settings, including cottage gardens, contemporary borders or patio gardens.

Hydrangeas are a common sight in UK gardens. These easy-to-grow deciduous shrubs have a long flowering period that lasts through the summer and autumn months. Dried hydrangea heads look beautiful displayed in a vase, but it's best to avoid completely deadheading hydrangeas. Leaving the flowerheads on the plant over winter helps protect the shrub from frost damage and adds valuable interest to your garden during the winter months. 

Mophead and panicle hydrangeas are typically the most popular varieties, though lacecap hydrangeas have a wonderfully elegant look. Certain varieties are renowned for their colour-changing flowers or vivid, true blue hues – a colour rarely found in the garden. There are also some scented varieties, including the popular red hydrangea, Hydrangea 'Whims Red', and Hydrangea 'Pinky Winky'.

 

Where to plant hydrangeas

Hydrangeas prefer moist soil in light shade. They don't love too much sun, but most varieties will cope with a sunny site, as long as they don't get too dry. Too much shade will impact flowering, and hydrangeas will really struggle to grow well in dry shade. The exception to this is the climbing hydrangea Hydrangea petiolaris. This shade-loving hydrangea is an excellent plant for brightening up a north or east-facing wall or shaded pergola.

Hydrangeas are hardy in the UK, but the young growth is sensitive to early frosts, so it's best to avoid exposed locations or frost pockets.

You can plant hydrangeas in alkaline, acidic and neutral soils. Cultivars of Hydrangea macrophylla, Hydrangea serrata and Hydrangea involucrata with blue or pink flowerheads change colour depending on the pH of the soil: in acidic soil, the flowers will be blue; in alkaline soils, they will turn pink.

When choosing hydrangeas for containers, go for compact cultivars of Hydrangea macrophylla and Hydrangea paniculata, such as Hydrangea 'Miss Saori' and Hydrangea 'Little Fresco'. 

 

When to plant hydrangeas

Plant hydrangeas in spring or autumn, when the soil is moist and warm. If you're planting at other times of the year, try to avoid periods when the ground is frozen or very dry. When planting hydrangeas in summer, make sure you water the shrubs regularly and deeply.

 

How to plant hydrangeas

Water your hydrangea plant well before planting. If you have dry or sandy soil, it's worth mixing some compost or other organic matter into the soil before you plant your hydrangea, as hydrangeas like the soil to be moist. If you want to treat your soil to adjust its pH, then do this before planting.

Dig a hold deep enough to hold the rootball of the plant and twice as wide. Plant your hydrangea so the soil is at the same level as in its planting pot, and backfill soil into the hole. Gently firm the soil and water well. It's worth adding a layer of mulch around the shrub to help the soil retain moisture.

How to grow hydrangeas in pots

Growing blue hydrangeas in pots is the easiest way to ensure your hydrangea flowers have the best colour, particularly if your soil is less acidic. Fill a large pot with ericaceous compost and select a blue hydrangea that's suitable for container growing, such as Hydrangea 'Blue Boogiewoogie'. Plant your hydrangea at the same level it was in its previous pot and water it in well.

When planting other hydrangeas in pots, use a peat-free compost with added John Innes.

 

How to care for hydrangeas

Hydrangeas need regular watering during their first spring and summer to help them establish. Mature hydrangeas will only need watering during very hot, dry spells or if they're planted in full sun. Use rainwater rather than water from your tap to water blue hydrangeas, as tap water is slightly alkaline. Hydrangeas grown in pots will need more regular watering; drench the pot until the water drains out of the bottom.

You don't need to feed hydrangeas unless your soil is particularly light and sandy. Mulching is more important, as hydrangeas get stressed if conditions are too dry. Mulch hydrangeas annually in spring.

Hydrangeas are hardy in the UK and don't require additional protection in winter. The young flower buds may suffer from frost damage; you can help prevent this by planting your hydrangea in a sheltered spot or moving container-grown shrubs if you live in a colder part of the country. Leaving the flowerheads on over winter can also help protect plants from frost damage.

When to prune hydrangeas

Pruning hydrangeas is best done in spring. The exact timing depends on the type of hydrangea. When pruning hydrangeas, cut the stems just above a pair of buds. 

Prune Hydrangea paniculata and Hydrangea arborescens cultivars in early spring, before new growth emerges. These hydrangeas produce flowers on new wood, so you can cut them back hard, down to the lowest pair of strong buds. If you want your shrub to be taller, prune higher up the stems.

Hydrangea macrophylla (mophead and lacecap hydrangeas) and Hydrangea serrata are best pruned in mid-spring, around March or early April, depending on where you are in the country. These hydrangeas bloom on wood from the previous year, so avoid pruning back to the base unless you want to rejuvenate an overgrown or leggy plant. Remove the flowerheads left on over winter, cutting back to the top pair of strong buds. For mature shrubs, you may want to remove one or two of the older stems completely to encourage fresh growth.

Hydrangea aspera, Hydrangea quercifolia and Hydrangea sargentiana don't need regular pruning, but you can cut back any dead branches and trim old flowerheads in spring.

The exception to the spring pruning rule is Hydrangea petiolaris (climbing hydrangea). You can trim this hydrangea in late summer once flowering is over, removing flowerheads and cutting back to a pair of buds. Go lightly – young plants may not need pruning at all. Hydrangea petiolaris doesn't respond well to hard pruning, and if you need to cut back an overgrown shrub, it's best to do this over several seasons.

 

How to propagate hydrangeas

Hydrangeas are usually propagated from cuttings, though you can collect hydrangea seeds from species hydrangeas and plant them if you fancy a challenge. Plants propagated from seed won't be identical to the parent plant. Hydrangea seeds need light to germinate, so surface sow the seeds either immediately after harvesting or the following spring.

How to take hydrangea cuttings

You can propagate hydrangeas by taking softwood cuttings in late spring or early summer, semi-ripe cuttings in late summer, or hardwood cuttings over winter.

Softwood cuttings are the quickest and easiest to root. Choose a non-flowering stem and remove the growing tip and all but the top two leaves – you may want to cut these in half if they're large. Trim the cutting so the base is just below a leaf node, dip it in hormone rooting compound and place it in a pot of cutting compost. The cutting should root in a few weeks.

 

Common problems

Hydrangeas don't suffer from many problems. If your hydrangea is struggling to grow or flower, it's likely due to too much shade, not enough water or pruning at the wrong time. Aside from environmental conditions, there are a couple of issues you may experience when growing hydrangeas.

Hydrangea scale insects can stunt growth in young plants and cause leaves to drop. The mature insects are brown, but the eggs are easier to spot as they're covered with a white, waxy substance.

Hydrangeas grown in pots can be affected by vine weevils. These severely damage the roots of plants and leave notch-shaped marks on the leaves. If you suspect vine weevils, lift your plant and look for the white larvae. You can use nematodes to treat infected plants and pick up adult insects.

If your colour-changing hydrangea has purple leaves, this could be a sign of phosphorus deficiency. Purple leaves can also be due to sudden drops in temperature in spring or autumn.

 

Our favourite varieties of hydrangea

It's tough to pick a favourite hydrangea, as there are so many varieties to choose from. Here's a selection of my favourites, but if you're not sure exactly what you want, browse our full range of hydrangea plants to see what catches your eye.

Hydrangea 'Annabelle' is arguably the most popular white hydrangea in the UK, due to its huge flowerheads which suit both contemporary and traditional garden designs and look wonderful in bouquets or dried flower arrangements. A more recent cultivar, Hydrangea 'Strong Annabelle', has more robust stems, which hold the flowerheads more upright.

Hydrangea 'Limelight' tops the rankings of panicle hydrangeas with its colour-changing flowerheads. The dense, conical panicles start out a vivid lime-green before maturing to cream in summer, with pink tinges later in the year.   

Hydrangea 'Glam Rock' is a dramatic mophead hydrangea with unusual colouring. The flowers are hot pink with lime tips and a blueish purple centre, but this hydrangea will change colour depending on the pH of your soil. In more alkaline soils, the lime colouring will be more prominent and the blue may fade altogether.

Hydrangea serrata 'Blue Bird' is a stunning blue hydrangea with large, lacecap flowers. It's relatively compact, growing up to 1.2 metres, and needs to be planted in soil with a pH below 6.5 (ideally pH 5.5) to get the strongest blue colour.

Hydrangea paniculata 'Vanille fraise' has beautiful two-tone pink and white flowerheads. This panicle hydrangea adds wonderful late season colour to a herbaceous border from mid-summer to mid-autumn.

 

FAQ

Can hydrangeas be pruned?

Pruning hydrangeas helps you get the best flowers and prevents plants from getting leggy. Mophead, lacecap, smooth and mountain hydrangeas benefit from pruning in spring, whereas climbing hydrangeas should be pruned after flowering in late summer.

When should you cut back hydrangea?

You should prune hydrangeas, with the exception of Hydrangea petiolaris (climbing hydrangea), in spring. You can cut back Hydrangea paniculata and Hydrangea arborescens hard in early spring, before growth starts. Prune Hydrangea macrophylla (mophead and lacecap hydrangeas) and Hydrangea serrata in March or early April. 

How do I prune my hydrangeas?

Mophead and lacecap hydrangeas and mountain hydrangeas flower on the previous year's growth. To prune these varieties, cut back to the top set or second set of buds in mid spring. Panicle hydrangeas and smooth hydrangeas (such as Hydrangea 'Annabelle') flower on new wood, so you can cut these back harder, to a strong pair of buds low down, in early spring. Other types of hydrangeas should only be pruned lightly to remove dead wood and flowerheads.

When do hydrangeas bloom?

Most hydrangeas bloom from summer to early autumn. Hydrangea 'Early Harry' is one of the earliest hydrangeas to flower, blooming from June to September. Hydrangeas are deciduous shrubs that drop their leaves in winter, but the dried flowerheads look beautiful throughout the colder months, adding valuable structure and interest to your borders.

Do hydrangeas like shade?

Most hydrangeas will grow well in partial or light shade, and in hot areas, many benefit from some shade from the afternoon sun. Only Hydrangea petiolaris, a climbing hydrangea, will grow well in full shade.