How to Grow Hydrangeas in the UK

Hydrangeas are one of the most rewarding shrubs you can grow in a UK garden. They love our mild, damp weather and flower reliably from June to October. Few shrubs give you such big, showy flowers for so little effort.

Grow them on acid soil and the flowers turn blue, while chalky ground keeps them pink. There’s a hydrangea for every garden, and below you’ll find the main types, plus how to plant, prune and feed them. Got a shady corner? Hydrangeas feature in our guide to the best plants for shade in UK gardens too.

Types of hydrangeas for UK gardens

Picking the right type comes first, because each grows, flowers and needs pruning a little differently. Our guide to types of hydrangeas compares lots of varieties.

Mophead hydrangeas (Hydrangea macrophylla)

Mopheads are the classic hydrangea, with big round flower heads from July to September. They come in blue, mauve, pink and white, depending on your soil.

Popular varieties:

• Endless Summer: Flowers on both old and new stems, so a late frost or a pruning slip won’t cost you all the flowers. Blue on acid soil, pink on chalky soil.
• Nikko Blue: A reliable deep blue on acid soil, with a neat, compact shape.
• Ayesha: Unusual cupped petals that look a bit like lilac, in pale pink or lilac-blue. Lightly scented.

Mopheads like shelter, as strong wind shreds the big flower heads. They look lovely in a cottage garden planting scheme with roses, foxgloves and lavender.

Lacecap hydrangeas (Hydrangea macrophylla)

Lacecaps are the same species as mopheads, but with flat flower heads: tiny flowers in the middle, ringed by bigger showy ones. They look lighter and more elegant.

Good varieties:

• Bluebird: Compact and reliable. Blue on acid soil, pink on chalky soil.
• Lanarth White: White outer flowers with blue or pink centres. Great in relaxed gardens.
• Mariesii Perfecta: Big flat heads in blue or pink, with nice autumn leaf colour.

Lacecaps are generally a bit tougher than mopheads and cope better with wind. They suit woodland-style gardens.

Lacecaps have tiny flowers in the middle and a ring of bigger ones round the edge. They cope with wind better than mopheads.

Paniculata hydrangeas (Hydrangea paniculata)

Paniculatas have cone-shaped flower heads. They flower on this year’s growth, so they’re easy to prune and late frosts don’t spoil the flowers.

Favourite varieties:

• Limelight: Big lime-green cones that fade to cream and pink. Grows quite tall.
• Vanilla Fraise: White cones that blush strawberry pink from the bottom up.
• Little Lime: A small version of Limelight, good for small gardens and big pots.
• Wim’s Red: White flowers that age through pink to deep wine-red.

Paniculatas cope with more sun and cold than mopheads. Their colour isn’t affected by soil.

Paniculatas flower on this year’s growth, so late frosts don’t spoil them. They also take more sun than mopheads.

Climbing hydrangea (Hydrangea anomala subsp. petiolaris)

Climbing hydrangea is one of the best self-clinging climbers for a shady wall. It grips with little aerial roots, so you don’t need trellis or wires. White lacecap flowers appear in early summer, and over time it can cover a whole north-facing wall.

It’s slow for the first couple of years, then gets going. After that it needs little more than trimming back shoots that stick out. It’s one of our best climbing plants for UK gardens.

Climbing hydrangea clings on by itself, so it needs no wires. It’s slow for a couple of years, then covers a shady wall beautifully.

Oakleaf hydrangea (Hydrangea quercifolia)

Oakleaf hydrangeas have leaves shaped like oak leaves and white cone-shaped flowers from July. The real show is in autumn, when the leaves turn crimson, orange and burgundy.

Good varieties:

• Snow Queen: Upright white flowers and great autumn colour. A reliable choice.
• Alice: Big flower heads and strong growth. Best in a sheltered garden.

Oakleafs like shelter and dislike cold winds and soggy clay. Improve drainage on clay soil before planting.

Hydrangea types at a glance

How to change hydrangea flower colour

Changing flower colour only works with mopheads and lacecaps. Paniculata, climbing and oakleaf hydrangeas stay the colour they are.

Why the colour changes

It all comes down to your soil. On acid soil, the plant can take up aluminium from the ground, and that turns the flowers blue. On chalky or alkaline soil, it can’t, so the flowers stay pink. Neutral soil often gives mauve or purple flowers.

Turning flowers blue

1. Test your soil with a simple kit from a garden centre.
2. On neutral soil, use a hydrangea blueing compound (aluminium sulphate), following the label.
3. Mulch with ericaceous compost or composted pine bark.
4. Avoid lime, wood ash and mushroom compost, which make soil less acid.
5. Use rainwater rather than tap water if you live in a hard water area.

You’ll see the change the following season, not on this year’s flowers. On very chalky soil, it’s much easier to grow blue hydrangeas in a pot of ericaceous compost.

In a hard water area, rainwater and a pine bark mulch help keep the soil acid. You’ll see the colour change next season.

Turning flowers pink

On acid soil, to get pink:

1. Sprinkle a little garden lime around the plant in autumn.
2. Use a general fertiliser rather than an ericaceous one.
3. Mulch with garden compost rather than pine bark.

Pink comes easily across much of England, where soils are often neutral to chalky. Blue is easier in Scotland, Wales and areas with sandy or peaty soil.

White hydrangeas

White varieties such as Annabelle and most paniculatas stay white whatever your soil. As they age, they often pick up green or pink tints.

How to plant hydrangeas

When to plant

The best time is October to March, while the plant is dormant. Autumn is ideal, as roots settle over winter. Pot-grown hydrangeas can go in at any time, but summer planting means lots of watering.

Choosing a spot

Most hydrangeas like morning sun and afternoon shade. That’s enough light for flowers without scorching the leaves.

Avoid:

• Hot, south-facing spots for mopheads and lacecaps, as their leaves scorch. Paniculatas cope with more sun.
• Deep shade, which gives leaves but few flowers. Climbing hydrangea is the exception.
• Windy spots, where big flower heads snap stems.
• Frost pockets, where late frosts can kill flower buds on mopheads and lacecaps.

Planting step by step

1. Dig a hole twice as wide as the root ball and the same depth.
2. Mix plenty of garden compost or well-rotted manure into the soil you dug out.
3. For blue flowers, add some ericaceous compost to the mix.
4. Plant at the same depth it was in the pot.
5. Fill back in, firming gently with your heel.
6. Water really well.
7. Spread a mulch of bark or garden compost around the base, keeping it off the stems.

Spacing

Allow 1-1.5m between mopheads and lacecaps, and 1.5-2m for paniculatas. Climbing hydrangeas eventually need plenty of wall space.

Pruning hydrangeas: the two groups

Pruning at the wrong time is the number one reason hydrangeas don’t flower. The trick is knowing which group yours belongs to.

Group 1: light trim in spring (mopheads, lacecaps, oakleaf)

These flower on last year’s stems. The buds form in late summer and autumn, then open the next summer. Cut those stems off and you lose the flowers.

When: Late March to mid-April, once hard frosts are over.

How:

1. Cut off old flower heads just above the first pair of fat, healthy buds below.
2. Remove any dead, damaged or crossing stems.
3. Take out one or two of the oldest, thickest stems at the base each year to encourage fresh growth.
4. Don’t cut the whole plant back hard unless it’s badly overgrown and you’re happy to lose a year’s flowers.

Handy tip: Leave the old flower heads on over winter. They help protect the buds below from frost and look lovely with a frosty coating. Remove them in spring when you see the new buds swelling.

Climbing hydrangea only needs a light trim after it flowers in summer, cutting back shoots that grow away from the wall.

Cut old mophead flower heads off just above the first pair of fat buds. Those buds carry this summer’s flowers, so leave them be.

Group 2: hard prune in late winter (paniculata, Annabelle)

These flower on this year’s growth, so pruning is simple and safe. You can cut them back hard every year and they’ll still flower.

When: Late February to early March, before new growth starts.

How:

1. Cut stems back to 30-45cm from the ground, or to a permanent framework of branches at the height you want.
2. Cut just above a pair of healthy buds.
3. Remove any dead or weak stems completely.
4. Strong new shoots will flower from July.

Annabelle does better with a slightly lighter cut, to about 45-60cm, so the stems are sturdy enough to hold up its big flower heads.

Paniculatas flower on new growth, so you can cut them back hard every February. Strong new shoots will flower from July.

Month-by-month hydrangea care calendar

Feeding hydrangeas

Hydrangeas don’t need much feeding, but the right feed at the right time helps them flower.

What to feed

• General fertiliser such as Growmore in March and again in June, following the label
• Liquid tomato feed every fortnight from April to August for plants in pots
• Ericaceous fertiliser for blue hydrangeas, to keep the soil acid
• Go easy on high-nitrogen feeds in summer, which give you leaves instead of flowers

Mulching

Spread a thick layer of mulch each spring. Bark, garden compost or well-rotted manure all work. It keeps the soil moist, stops weeds and feeds the soil. For blue flowers, use composted pine bark rather than garden compost.

The RHS growing guide for hydrangeas is a good place for more detail.

Growing hydrangeas in containers

Hydrangeas make great pot plants. It’s also the easiest way to choose the flower colour, because you pick the compost.

Choosing a pot

• Go big. Hydrangea roots need room.
• Drainage holes are a must, as hydrangeas hate sitting in water.
• Terracotta looks lovely but dries out fast. Line it with polythene, with holes punched in the bottom.
• Glazed or plastic pots hold moisture better.

Compost choice

• For blue flowers: ericaceous (lime-free) compost
• For pink flowers: John Innes No. 3 (loam-based)
• For white varieties: any good loam-based compost

Looking after potted hydrangeas

Water daily in summer, as hydrangeas in pots are very thirsty. Feed every fortnight with tomato feed from April to August. Repot every two or three years in spring, moving up a pot size.

In winter, raise pots on feet or bricks so they don’t get waterlogged. In colder parts of the country, wrap pots in bubble wrap or hessian, as roots in pots freeze more easily than those in the ground.

Best varieties for pots

Common mistakes when growing hydrangeas

Pruning at the wrong time

Cutting mopheads and lacecaps back hard in autumn or winter removes next year’s flower buds. Only trim them lightly in late March or early April. Paniculatas are the opposite and like a hard cut in late February.

Planting in full sun

Hydrangeas are woodland-edge plants. In full south-facing sun the leaves scorch, they wilt in the afternoon heat and the flowers fade fast. Morning sun and afternoon shade is the sweet spot.

Waterlogged roots in winter

Hydrangeas need plenty of water in summer but hate sitting wet in winter. On heavy clay, improve clay soil drainage before planting by digging in grit and organic matter. Raise pots off the ground from October to March.

Using the wrong feed for flower colour

Some general feeds can make blue hydrangeas turn a muddy purple. For blue, stick to an ericaceous feed. For pink, use a balanced feed and avoid ericaceous products.

Forgetting about late frost

Frosts in April and May can kill the new flower buds on mopheads and lacecaps. In a frost pocket, throw fleece over them when frost is forecast, or grow paniculatas, which aren’t affected.

A late frost can blacken new shoots and kill the flower buds. Throw fleece over mopheads and lacecaps when frost is forecast in spring.

Hydrangea pests and diseases

Hydrangeas are generally healthy. Here’s what to watch for:

Vine weevil: The grubs eat roots, especially in pots, and adults notch leaf edges. Water in vine weevil nematodes in late summer, and pick out any creamy C-shaped grubs when repotting.

Powdery mildew: A white powdery coating on leaves in dry summers. Thin out crowded stems and water the roots, not the leaves. It’s rarely serious.

Hydrangea scale: Brown, limpet-like bumps on stems. Scrape them off by hand in winter.

Honey fungus: The most serious problem, causing dieback and death, with honey-coloured toadstools at the base in autumn. There’s no cure. Dig out the affected plant and don’t replant a hydrangea in the same spot.

Pets: Hydrangeas are mildly toxic if dogs or cats eat them. See our guides to plants toxic to dogs and plants toxic to cats.

Frost damage: Blackened shoot tips and shrivelled buds after a late frost. Snip off damaged growth in May, once you can see healthy buds below.

Propagating hydrangeas

Hydrangeas are one of the easiest shrubs to make more of. Cuttings taken in August usually root well.

1. Choose a shoot without a flower, about 10-15cm long.
2. Cut just below a leaf joint.
3. Remove all but the top pair of leaves.
4. Cut those leaves in half so the cutting doesn’t lose too much water.
5. Dip the base in hormone rooting powder.
6. Push it into a pot of half perlite and half multipurpose compost.
7. Cover with a clear plastic bag or pop it in a propagator.
8. Keep moist and out of direct sun. Roots form in a few weeks.
9. Pot up separately in spring and grow on for a year before planting out.

Layering is even easier. In spring, bend a low branch to the ground, make a small nick underneath, pin it down and cover with soil. Once it has rooted, usually by the next spring, cut it free from the parent.

Now you’ve got hydrangeas sorted, read our guide on the best plants for shade in UK gardens for more plants to grow alongside them.

Frequently asked questions

When is the best time to plant hydrangeas in the UK?

October to March is the best time. Planting in autumn lets the roots settle over winter before spring growth starts. Pot-grown plants can go in at any time, but avoid frozen or waterlogged ground and hot, dry spells.

Why are my hydrangea flowers turning green?

It’s completely normal in late summer. As the flowers age from August onwards, they slowly fade to green. It isn’t a disease or a feeding problem, and nothing you’ve done wrong. Many people love the antique look.

Can I grow hydrangeas in full shade?

They prefer part shade to full shade. Most need a few hours of light a day to flower well. In deep shade you’ll get healthy leaves but few flowers. Climbing hydrangea is the best choice for a really shady wall.

How do I turn my hydrangea flowers blue?

You need acid soil, which gives blue flowers. On neutral soil, use a hydrangea blueing compound as the label says, and mulch with ericaceous compost. Water with rainwater in hard water areas, and avoid lime. It takes a season to see the change.

When should I prune my hydrangea?

Trim mopheads and lacecaps lightly in late March or early April. Prune paniculata and Annabelle types harder in late February. Never cut mopheads or lacecaps back hard in autumn or winter, because that removes next year’s flower buds.

Can I grow hydrangeas in pots?

Yes, they grow well in big pots. Use a large pot with drainage holes, filled with loam-based compost for pink flowers or ericaceous compost for blue. Water daily in summer and feed every fortnight with tomato feed from April to August.

Why is my hydrangea not flowering?

Usually it’s been pruned at the wrong time. Mopheads and lacecaps flower on stems that grew last year, so cutting them back hard removes the buds. Late frosts can also kill the buds, so cover plants with fleece if frost is forecast in spring.