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Shrubs

Hydrangea serrata (Amacha Group) 'Ō-amacha' (L)

hydrangea 'Ō-amacha'

A bushy shrub to around 1.3m high with narrowly-ovate green leaves and flowerheads comprising small, blue or pink, fertile florets surrounded by sterile white florets that become stained and speckled pinkish-red with age

Synonyms

Hydrangea macrophylla 'Oamacha'

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Ultimate height

1–1.5 metres

Time to ultimate height

5–10 years

Ultimate spread

1–1.5 metres

Clay

Loam

Moisture

Moist but well–drained

pH

Acid, Neutral

	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Partial shade

Aspect

East–facing or North–facing or South–facing or West–facing

Exposure

Sheltered

Hardiness
Hardiness ratings
All ratings refer to the UK growing conditions unless otherwise stated. Minimum temperature ranges (in degrees C) are shown in brackets
H1a: under glass all year (>15C)
H1b: can be grown outside in the summer (10 - 15)
H1c: can be grown outside in the summer (5 - 10)
H2: tolerant of low temperatures, but not surviving being frozen (1 to 5)
H3: hardy in coastal and relatively mild parts of the UK (-5 to 1)
H4: hardy through most of the UK (-10 to -5)
H5: hardy in most places throughout the UK even in severe winters (-15 to -10)
H6: hardy in all of UK and northern Europe (-20 to -15)
H7: hardy in the severest European continental climates (< -20)

Botanical details

Family: Hydrangeaceae
Native to the UK: No
Foliage: Deciduous
Habit: Bushy
Potentially harmful: Skin allergen. Wear gloves and other protective equipment when handling. Pets (dogs, cats): Harmful if eaten. For further information and contact numbers regarding pets, see the HTA guide to potentially harmful plants
Genus: Hydrangea can be deciduous or evergreen shrubs, or self-clinging climbers, with flowers in clusters usually comprising both small fertile and more showy sterile flowers; often good autumn colour
Name status: Accepted
Horticultural Group: Lace cap hydrangeas are compact deciduous shrubs with broadly ovate leaves and flat or gently domed clusters of small fertile flowers, with showy sterile flowers around the margin

How to grow

Cultivation

Grow in any moist but well-drained soil in partial shade or grow in sun if soil remains reliably moist. Improve chalky soils with organic matter to support good growth. See shrubby hydrangea cultivation for further advice

Propagation

Propagate by softwood or hardwood cuttings

Suggested planting locations and garden types

City and courtyard gardens
Cottage and informal garden
Cut flowers
Flower borders and beds

Pruning

See pruning group 4 for further advice and video guide

Pests

May be susceptible to aphids, capsid bug, hydrangea scale and vine weevils

Diseases

May be susceptible to a leafspot, grey moulds, powdery mildews and honey fungus

Get involved

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