Shrub
Bigleaf hydrangea
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Flowers | Flowers in July | Flowers in August | Flowers in September | |||||||||
| Plant | Plant in March | Plant in April | Plant in October | Plant in November | ||||||||
| Prune | Prune in March | |||||||||||
| Looks good | Looks good in July | Looks good in August | Looks good in September | Looks good in October |
Overview
Mopheads carry rounded domes of sterile flowers, while lacecaps have a flat centre of tiny fertile florets ringed by showy petals, which pollinators find more useful. Flower colour depends on soil: acid ground gives blue, alkaline gives pink, and white varieties stay white either way. 'Mariesii Perfecta' is a reliable blue lacecap, and the Endless Summer types flower on new growth too, which helps after a hard frost.
Where to grow bigleaf hydrangea
A spot with morning sun and afternoon shade suits them best; a north- or east-facing border is ideal. They wilt quickly in hot, dry gardens, so avoid shallow soil under trees. Hostas and Japanese anemones make easy, shade-tolerant companions.
Planting
Plant in spring or autumn into soil enriched with plenty of compost or leaf mould. Set the plant at the same depth it sat in its pot and water it in thoroughly. In containers use a peat-free ericaceous compost if you want to keep blue flowers blue.
Care through the year
Spring
Mulch generously in April to lock in moisture and feed with a general fertiliser.
Summer
Water deeply in dry weather, especially in the first two years; limp leaves at midday are the warning sign.
Autumn
Leave the fading heads in place, as they turn attractive shades of green, red and parchment.
Winter
The old heads protect next year's buds from frost, so resist tidying until spring.
Pruning
Bigleaf hydrangeas flower on buds formed the previous year. In March, cut each old flower head back to the first strong pair of buds below it. On mature plants, also remove one or two of the oldest, weakest stems at the base to keep the shrub young. Hard pruning in autumn removes the flowers.
Propagation
Softwood cuttings root readily in early summer. Take non-flowering shoot tips, remove the lower leaves, halve the large upper leaves and pot them in gritty compost under a plastic bag.
Common problems
Late spring frosts can blacken new shoots and buds, so a sheltered spot pays off. Vine weevil grubs attack plants in pots. Powdery mildew and grey mould sometimes appear in stuffy, dry corners; improving watering and airflow usually solves it.
Guides to the problems most likely to affect bigleaf hydrangea:
Something else wrong? Diagnose it by symptom.
Month-by-month reminders
Jobs for this plant come round in March, April, October and November. Each month page lists everything else worth doing in the garden at the same time.
Related plants
Sources
Botanical names follow Kew's Plants of the World Online; growing attributes were checked against the references below. Text is our own. See our editorial policy.