Hydrangea macrophylla Care: Growing Guide

Few shrubs deliver such generous, long-lasting colour as Hydrangea macrophylla, the classic mophead and lacecap hydrangea of cottage gardens and coastal borders. Its enormous domed or flat flowerheads open in midsummer and persist well into autumn, fading gracefully to antique parchment shades. Most remarkably, the flower colour of many cultivars shifts from pink to blue depending on the acidity of your soil — a living litmus test in the border.

Growing conditions

Bigleaf hydrangeas are woodland-edge plants at heart, so they perform best in dappled or partial shade with shelter from harsh afternoon sun. Morning sun with midday shade is close to ideal. In deep shade, plants grow leafy but flower sparsely.

Give them a moist, humus-rich, well-drained soil that never bakes dry — those enormous leaves lose water rapidly. Heavy clay improved with leaf mould or garden compost suits them well, whilst thin chalk and dry sand are a struggle. Soil pH determines flower colour: below pH 5.5 blooms turn blue, above pH 6.5 they turn pink, and in between you get muddled mauves.

They are fully hardy in most of Britain and northern Europe, though late spring frosts can scorch the emerging flower buds. Coastal gardens suit them particularly well, as salt-laden air rarely troubles them and humidity is high.

How to plant Hydrangea

Plant in autumn or early spring, when the soil is warm and moist enough for roots to establish before the plant faces summer drought stress. Avoid planting during hot, dry midsummer spells.

Space plants 1.2–1.5 m apart so air circulates freely and mature shrubs are not forced to compete — closer spacing encourages mildew.
Set the rootball so its surface sits level with the surrounding soil; planting too deeply causes stem rot.
Fork plenty of leaf mould, composted bark or well-rotted manure into the planting area to hold moisture.
Water in with at least 10 litres per plant and mulch 5–7 cm deep, keeping the mulch clear of the stems.
Propagate from softwood cuttings in June, taking 10 cm non-flowering shoots — they root readily in a shaded cold frame within six weeks.

Hydrangea macrophylla growing in a garden border — Hydrangea macrophylla growing in a naturalistic garden border

Care through the seasons

Spring: Wait until the buds break, then cut last year’s faded flowerheads back to the first pair of fat, healthy buds. Remove any dead, weak or crossing stems at the base to open up the centre. Apply a balanced slow-release feed and a generous mulch of compost.

Summer: Water deeply and regularly — a mature shrub may need 15–20 litres a week in dry spells, and container plants need daily attention. Wilting leaves in the afternoon heat are common but should recover by evening; if not, water urgently. Feed blue-flowered cultivars with a sulphate of aluminium tonic if the colour is drifting towards pink.

Autumn: Leave the spent flowerheads on the plant rather than tidying them away, as they shield next year’s buds from frost. Top up mulch around the base once the leaves have fallen. This is the best moment to plant new specimens or move established ones.

Winter: The shrub is fully dormant and bare, its buds already formed on last summer’s wood. In cold or exposed gardens, wrap young plants in fleece or pile bracken around the crown to protect those precious flower buds.

Best varieties to grow

Choose according to whether you prefer the bold globes of mopheads or the subtler, pollinator-friendly lacecaps.

‘Zorro’ — A superb lacecap with near-black stems and violet-blue florets, holder of the RHS Award of Garden Merit.
‘Ayesha’ — Unusual cupped, lilac-scented florets that resemble a lilac more than a hydrangea; slow and elegant.
‘Mariesii Perfecta’ (Blue Wave) — A classic AGM lacecap with airy blue or lilac heads, excellent in light woodland.
Endless Summer ‘Bailmer’ — Reblooming mophead that flowers on both old and new wood, useful where late frosts are a risk.

Pests, diseases and common problems

Powdery mildew: A greyish-white bloom coats the leaves in humid, crowded conditions. Thin congested stems to improve airflow, water at the roots rather than overhead, and remove affected foliage.
Vine weevil: Adults notch the leaf margins whilst the grubs devour roots in containers, causing sudden collapse. Drench pots with parasitic nematodes (Steinernema kraussei) in late summer when soil is above 5 °C.
Failure to flower: Almost always caused by pruning in autumn or winter, or by frost damage to buds. Prune only in spring after bud break, and fleece plants when hard frosts threaten.

Frequently asked questions

Key tip: Hydrangea macrophylla flowers on wood produced the previous summer, so never cut it back hard in autumn or you will remove every bloom.

How do I turn my hydrangea flowers blue?

Blue colouring requires available aluminium, which only dissolves in acid soil below about pH 5.5. Apply sulphate of aluminium (hydrangea colourant) every fortnight from early spring, water with rainwater rather than hard tap water, and mulch with ericaceous compost. On chalky soil, growing in a pot of ericaceous compost is far more reliable.

Why is my hydrangea wilting even though I water it?

Large leaves lose moisture faster than roots can replace it, so temporary afternoon wilting in full sun is normal and reverses overnight. Persistent wilting usually signals dry roots, waterlogging or vine weevil damage — dig gently and check the rootball. Move sun-baked plants to partial shade and mulch thickly to stabilise soil moisture.

When should I prune Hydrangea macrophylla?

Prune in March or early April, once the buds have swollen and you can clearly see which wood is alive. Cut each faded flowerhead back to the first strong pair of buds, and remove up to a quarter of the oldest stems at ground level to rejuvenate the shrub. Never shear the whole plant back in autumn.

Is Hydrangea macrophylla a good choice for a north-facing garden?

Yes — it is one of the finest flowering shrubs for cool, north-facing beds, provided the site is not in dense dry shade beneath trees. Compared with Hydrangea paniculata, which demands more sun, macrophylla thrives on gentle light and consistent moisture. Expect slightly later flowering and marginally fewer blooms than in a brighter spot.