Hydrangea aspera subsp. robusta

RHS Plant Profile

Himalyan tree hydrangea

Other common names

robust hydrangea

Synonyms

Hydrangea aspera 'Rosthornii'
Hydrangea robusta
Hydrangea rosthornii

Shrubs

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An erect, deciduous shrub to 6m tall, with softly hairy, lance-shaped leaves to 29cm long with red petioles. Produces flat flowering heads with blue-purple fertile flowers and showy white outer sterile flowers in late summer

Position

Full sun, Partial shade

Soil Types

Clay, Loam, Sand

Max Height

1.5-2.5 metres

Max Spread

1-1.5 metres

Size

Time to Maturity: 10–20 years
Max Spread: 1-1.5 metres
Max Height: 1.5-2.5 metres

Growing Conditions

Clay Loam Sand

Moisture: Moist but well–drained
pH: Acid or Neutral

Position

Full sun Partial shade

Aspect: East–facing or South–facing or West–facing or North–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): H5

Colour & Scent

Season	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family: Hydrangeaceae
Native to GB/Ireland: 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: Correct
Plant Range: S Asia

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 cuttings in early summer

Suggested planting locations and garden types

City and courtyard gardens
Cottage and informal garden
Flower borders and beds
Wall side borders

Pruning

Pruning group 1

Pests

May be susceptible to aphids, capsid bug and hydrangea scale

Diseases

May be susceptible to a leaf spot