Bigleaf hydrangea

Sun

Morning sun and afternoon shade are ideal. Tolerates more sun in cool climates if the soil stays moist; protect from hot afternoon sun and drying winds.

Water

Keep the root zone consistently moist but not waterlogged. Water deeply during dry weather, especially in the first two growing seasons; containers may need daily checks in summer.

Soil

Fertile, moisture-retentive soil with good drainage. Acid soil with available aluminium encourages blue flowers in responsive varieties; less acidic soil usually produces pink flowers. White varieties generally stay white.

Height

3-6 ft (0.9-1.8 m)

Spread

3-6 ft (0.9-1.8 m)

Flowers

Early summer to early autumn, depending on cultivar and climate; pink, blue, purple or white mophead or lacecap flower heads. Many older cultivars flower mainly in early to midsummer.

Foliage

Broad, toothed, usually glossy green leaves; autumn colour is variable and often modest.

Growth

Moderate; size varies considerably by cultivar and growing conditions.

Care needed

Medium

• Water at soil level, soaking the root zone rather than giving frequent light sprinkles.
• Apply 2-3 in (5-8 cm) of organic mulch each spring, keeping it clear of the stems.
• Feed lightly in spring with a balanced shrub fertiliser if growth is weak; excess nitrogen encourages leaves rather than flowers.
• Protect emerging shoots and flower buds with horticultural fleece when late frost is forecast.
• Use a large container with drainage holes and moisture-retentive potting mix; do not leave the pot standing in water.

Pruning. Most cultivars flower on old wood: in spring, remove dead stems and cut last year's flower heads back to the first healthy pair of buds; shorten live stems only if necessary, immediately after flowering. Reblooming cultivars also flower on new growth, but hard pruning can still remove their early display.

Late winter

Leave old flower heads in place in frost-prone gardens; check that container drainage holes remain clear.

Spring

Once buds show clearly, remove dead wood and old flower heads without cutting away healthy flowering shoots.

Spring

Refresh the mulch and feed lightly if needed; protect new growth during late frosts.

Early summer

Check soil moisture regularly and begin deep watering during dry spells.

Summer

Take softwood cuttings from healthy, non-flowering shoots.

After flowering

If the shrub needs reducing, shorten selected stems promptly rather than shearing the whole plant.

Autumn

Plant while soil is moist and workable, avoiding frozen or waterlogged ground; protect container roots before severe winter cold.

• Group beneath lightly shading trees with ferns and hostas for a broad-leaved woodland border.
• Plant along a sheltered path or near a seating area where the flower heads can be seen closely.
• Use repeated groups in a mixed shrub border for a continuous band of summer colour.
• Grow a compact cultivar in a large courtyard container with afternoon shade and reliable watering.

Garden styles it suits: Cottage garden, English country, Woodland, Traditional, Japanese and Coastal.

Plant it with: Hostas, Japanese painted ferns, Astilbes, Camellias, Azaleas and Japanese forest grass.

Wildlife: Lacecap flowers provide more accessible pollen and nectar than mopheads, whose large showy florets are mostly sterile. Dense growth offers small animals shelter, but this is not a particularly high-value wildlife shrub.

• Few or no flowers: winter cold, late frost or hard pruning may have killed or removed flower buds. Choose a sheltered position and preserve healthy old wood; avoid excessive nitrogen feeding.
• Wilting or scorched leaves: check soil moisture before watering. Water deeply if dry and provide afternoon shade; wilting in wet soil can indicate poor drainage or root damage.
• Powdery mildew or leaf spots: improve airflow, water the soil rather than the leaves, and clear fallen infected foliage. Mild late-season spotting rarely needs treatment.
• Aphids or scale insects: inspect shoots and leaf undersides; wash off aphids and treat persistent infestations with a labelled insecticidal soap or horticultural oil.

Toxic to cats, dogs, horses and people if eaten. All parts contain cyanogenic glycosides, especially leaves and flower buds; ingestion commonly causes stomach upset, vomiting or diarrhoea. Serious poisoning is uncommon but possible after substantial ingestion; seek medical or veterinary advice if eaten.

Where it spreads. Invasive in the Azores, Portugal, where escaped plants can spread into semi-natural vegetation. Check local restrictions before planting there.

• Mountain hydrangea (Hydrangea serrata)

  Usually smaller and finer-textured, with narrower, less glossy leaves and often delicate lacecap flowers. Hybrids between the two can be difficult to distinguish.

• Smooth hydrangea (Hydrangea arborescens)

  Usually has thinner, less glossy leaves and white or pink flower heads that do not turn blue in acid soil; it flowers on the current season's growth.

• Panicle hydrangea (Hydrangea paniculata)

  Has cone-shaped rather than rounded or flat flower heads, usually opening white or greenish and often ageing pink; flowers form on new growth.

Hydrangea comes from Greek words meaning water vessel, referring to the seed capsules, while macrophylla means large-leaved.

Propagation. Take softwood cuttings from non-flowering shoots in late spring or early summer, keeping them humid and out of direct sun until rooted. Low branches can also be layered; seed does not reliably reproduce a named cultivar.

Accepted botanical name

Hydrangea macrophylla

Native range

Japan and Kazan-retto.

Measured

Soil pH 4.5 to 8. Average height 150 cm.

Sources: GBIF (CC BY 4.0) and Trefle (CC BY 4.0). The care and design notes are LandscapeGPT's own.