Spiraea thunbergii

RHS Plant Profile

Thunberg spiraea

RHS 2003

Shrubs

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A dense, bushy deciduous shrub about 1.5m tall, with narrow light green leaves to 4cm in length. White flowers 6mm in width are borne in abundant small clusters along the branches, in early spring

Position

Full sun, Partial shade

Soil Types

Chalk, Loam, Sand, Clay

Max Height

1-1.5 metres

Max Spread

1-1.5 metres

Size

Time to Maturity: 5–10 years
Max Spread: 1-1.5 metres
Max Height: 1-1.5 metres

Growing Conditions

Chalk Loam Sand Clay

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

Position

Full sun Partial shade

Aspect: East–facing or South–facing or North–facing or West–facing
Exposure: Exposed or 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): H6

Colour & Scent

Season	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family: Rosaceae
Native to GB/Ireland: No
Foliage: Deciduous
Habit: Bushy
Genus: Spiraea are deciduous shrubs, sometimes suckering, with simple leaves and short racemes, panicles or corymbs of small, 5-petalled white or pink flowers in spring or summer
Name Status: Correct
Plant Range: China Japan

How to Grow

Cultivation

Grow in moist but well-drained soil in full sun or light shade. Especially suitable for mixed borders

Propagation

Propagate by softwood or semi-ripe cuttings in spring to late summer or hardwood cuttings in winter

Suggested planting locations and garden types

City and courtyard gardens
Coastal
Cottage and informal garden
Flower borders and beds

Pruning

Pruning group 2. If overgrown, can be renovated by cutting back hard immediately after flowering

Pests

Generally pest-free

Diseases

Generally disease-free but may be susceptible to honey fungus