How to grow Hydrangea

Hydrangea macrophylla · bigleaf hydrangea, mophead hydrangea, lacecap hydrangea

A deciduous shrub with large mophead or lacecap flower clusters in July and August, blue in acid soil and pink in neutral to alkaline soil. It flowers on last year's wood. All parts are toxic to cats, dogs and horses.

Quick facts

Type	Flower
Family	Hydrangeaceae
Light	Partial shade
Soil pH	5–7
Frost	tolerates light frost
Soil for sowing	from 5 °C
Germination	28 days
Where it grows	Greenhouse, Open ground, At home

When to plant

Planted as a young plant from a nursery while it is dormant — in early spring before the buds open, or in autumn after leaf fall.

Frost dates · When to plant

Care

Greenhouse

Stage	Watering	Temperature	Feeding
Germination	every 4 days	—	—
Growth	every 4 days	—	balanced (NPK), at the start of the stage; balanced (NPK), 28 days into the stage
Flowering	every 4 days	—	balanced (NPK), 7 days into the stage

Open ground

Stage	Watering	Temperature	Feeding
Germination	every 7 days	—	—
Growth	every 7 days	—	balanced (NPK), at the start of the stage; balanced (NPK), 28 days into the stage
Flowering	every 7 days	—	balanced (NPK), 7 days into the stage

At home

Stage	Watering	Temperature	Feeding
Germination	every 3 days	—	—
Growth	every 3 days	—	—
Flowering	every 3 days	16…18 °C	—

Growing notes

Light

Morning sun and afternoon shade; avoid hot, exposed sites. It takes full sun only where the soil stays moist.

Soil

Rich, moist, well-drained soil with plenty of organic matter. Flowers are blue at pH 5.0–5.5 and pink at pH 6.0 and above; white cultivars do not change. Mulch to keep the roots moist.

Care

Plant in spring or autumn with the top of the root ball level with the soil, and space plants as wide as they grow (about 1–1.8 m). Water deeply once a week, more in dry spells. Once established, feed a balanced fertiliser in spring, May and July. Prune right after flowering, cutting flowered stems back to a pair of healthy buds, and never after early August, because next year's buds form in late summer. Cover the plant on freezing nights to protect the buds. A potted gift hydrangea indoors needs bright, indirect light, a cool room (16–18 °C) and soil kept evenly moist.

Pests and diseases of Hydrangea

Sources

Figures checked against these sources.