How to Care for Hydrangeas

Hydrangeas are among the most popular garden shrubs, loved for their large, showy flower heads. With the right care, they are easy to grow and will reward you with blooms for many years.

Types of hydrangea

• Mophead (H. macrophylla): Round flower heads, blue or pink depending on soil pH.
• Lacecap (H. macrophylla): Flat flower heads with tiny flowers in the centre.
• Panicle (H. paniculata): Cone-shaped white flowers that age to pink.
• Climbing (H. petiolaris): Self-clinging climber with white lacecap flowers.
• Oak-leaved (H. quercifolia): Distinctive lobed leaves and white flowers.

Where to plant

Most hydrangeas prefer partial shade, especially in the afternoon. They can tolerate full sun if the soil stays moist, but flowers may fade in hot weather. Avoid very exposed sites where cold winds can damage flower buds.

They like moist, well-drained soil enriched with organic matter. Heavy clay or very dry soil should be improved before planting.

Watering

Hydrangeas need plenty of water, especially in summer. The name comes from the Greek for "water vessel" – a clue to their thirst. Water deeply during dry spells and mulch to retain moisture.

Wilting leaves in hot weather usually mean the plant needs water. Container-grown hydrangeas may need watering daily in summer.

Feeding

Apply a balanced fertiliser in spring as growth begins. Avoid high-nitrogen feeds which encourage leaves at the expense of flowers. A mulch of well-rotted compost or manure in spring provides nutrients and helps retain moisture.

Pruning

Pruning depends on the type:

• Mophead and lacecap: In early spring, remove dead flower heads, cutting back to the first strong pair of buds. Do not cut into old wood unless rejuvenating an overgrown plant.
• Panicle and smooth hydrangeas: Can be pruned hard in late winter – they flower on new growth.
• Climbing hydrangeas: Prune after flowering if needed to control size.

If you prune mopheads too hard or at the wrong time, you may remove next year's flower buds.

Changing flower colour

Mophead and lacecap hydrangeas can be blue or pink depending on soil pH:

• Acid soil (pH below 6): Flowers are blue.
• Alkaline soil (pH above 7): Flowers are pink.
• Neutral soil: Flowers may be purple or mixed.

To make flowers bluer, add aluminium sulphate or ericaceous compost. To make them pinker, add lime. White varieties stay white regardless of soil pH.

Winter protection

Most hydrangeas are hardy, but late frosts can damage flower buds on mopheads and lacecaps. In cold areas, protect with fleece if frost is forecast after buds have started to swell in spring.

Common problems

• No flowers: Usually caused by pruning at the wrong time or frost damage to buds.
• Wilting: Needs more water.
• Yellow leaves: May indicate lime-induced chlorosis in alkaline soil. Use ericaceous compost and feed.