How to Grow Hydrangea (Mophead/Lacecap)
Hydrangea macrophylla
Hydrangeas thrive in moist, humus-rich, free-draining soil and partial shade (morning sun, afternoon shade). Plant at pot level, mulch annually, and water deeply in dry spells. Buds form in summer for next year, so avoid hard pruning. In spring, remove old flower heads and cut one in three oldest stems to the base. Flower colour depends on soil chemistry; blue shades prefer acidic conditions, pink prefers alkaline.
Yearly Lifecycle
Care Essentials
Spring with a balanced fertiliser. Ericaceous feed for blue-flowering varieties on neutral soil.
Watch For
- Vine weevil
- Hydrangea scale
- Powdery mildew
- Honey fungus
- Frost damage to flower buds
Companions
Hostas, Ferns, Astilbe, Heuchera
Pet Safety
Care Requirements
Light
Morning sun, afternoon shade; avoid hot south walls
Morning sun with afternoon shade is ideal. Avoid hot south-facing walls which scorch leaves. Deep shade reduces flowering.
Watering
Water deeply and regularly; mulch to retain moisture
Water deeply and regularly, especially in dry spells — hydrangeas are thirsty plants. Mulch to retain moisture. Wilting in afternoon heat is common even in moist soil.
Fertilizing
Balanced spring feed; ericaceous feed for blue flowers
Apply a balanced fertiliser in spring. For blue flowers on macrophylla types, use ericaceous feed or aluminium sulphate. Avoid lime-based feeds if you want blue blooms.
Pruning
Remove old heads in spring; flowers on old wood; avoid hard pruning
Remove spent flower heads and cut one in three oldest stems to the base in spring. Flowers form on old wood, so avoid hard pruning. Leave old heads on over winter to protect buds.
Mulching
Annual compost mulch to conserve moisture
Mulch annually with compost or leaf mould to conserve moisture and improve soil. This is especially important on free-draining soils where hydrangeas can suffer drought stress.
Growing Tips
Prune lightly in spring
Macrophylla hydrangeas flower on old wood, so only remove spent heads and thin old stems in spring. Hard pruning removes next year's blooms.
Water deeply
A thorough soak less often is better than frequent sprinkles; mulch to hold moisture.
Leave old heads over winter
Spent blooms protect tender buds; remove in spring when frosts pass.
Tweak colour carefully
For blues, maintain slight acidity with ericaceous compost or aluminium sulphate; for pinks, avoid acidifying inputs.
Pests & Diseases
Pest Vine Weevil
Identification: Notched leaf edges from adult feeding at night; wilting and collapse from root-feeding larvae in pots
- Apply Heterorhabditis nematodes to compost in late summer
- Check root balls when repotting and destroy cream-coloured C-shaped larvae
- Drench containers with acetamiprid-based vine weevil killer
Pest Hydrangea Scale
Identification: White, oval, waxy scales on stems and leaf undersides; sticky honeydew and sooty mould
- Scrub off with a soft brush or cloth dipped in soapy water in winter
- Encourage natural predators such as parasitic wasps
- Spray with plant oil winter wash while dormant
- Contact insecticide in early summer when crawlers are active
Pest Capsid Bug
Identification: Ragged holes in young leaves; distorted flower heads; bugs rarely seen as they drop when disturbed
- Clear plant debris where bugs overwinter
- Damage is usually cosmetic — plants recover
- Contact insecticide spray at first sign of damage
Disease Powdery Mildew
Symptoms: White powdery coating on leaves, especially on the undersides; leaves may curl and brown
Treatment: Improve air circulation; remove badly affected leaves
Prevention: Avoid overcrowding; water at the base; ensure good airflow around plants
Disease Honey Fungus Armillaria mellea
Symptoms: Sudden wilting and death of branches or the whole plant; white fungal sheets under the bark at the base; honey-coloured toadstools in autumn
Treatment: Remove and destroy the entire plant including as much root as possible; do not replant susceptible species in the same spot
Prevention: Maintain plant vigour; install a physical root barrier if honey fungus is known in the area
Disease Grey Mould (Botrytis) Botrytis cinerea
Symptoms: Fuzzy grey fungal growth on fading flowers and damaged stems, especially in cool, wet weather
Treatment: Remove affected flowers and growth promptly; improve ventilation
Prevention: Deadhead spent blooms; avoid overcrowding; water at the base
Popular Varieties
Mophead
Lacecap
Endless Summer
The original remontant (reblooming) bigleaf hydrangea that flowers on both old and new wood. Colour shifts from pink in alkaline soil to blue in acidic.
Incrediball
An arborescens hydrangea producing enormous white snowball flower heads up to 30cm across on strong stems that resist flopping. Extremely cold hardy.
