Acer rubrum 'Sun Valley'

RHS Plant Profile

red maple 'Sun Valley'

Trees

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An oval to round-headed, deciduous tree about 10m tall. The 3-5 lobed palmate are leaves to 10cm long. The new spring growth is reddish-green, maturing to bright green in summer, then turning brilliant, fiery red in autumn if the weather is reliably cold. Upright clusters of tiny red flowers are borne in spring followed by dark red winged fruits in autumn. This selection keep its autumn tones for longer than other cultivars and its canopy especially symmetrical in shape

Position

Full sun, Partial shade

Soil Types

Clay, Loam, Sand

Max Height

8-12 metres

Max Spread

4-8 metres

Size

Time to Maturity: 20–50 years
Max Spread: 4-8 metres
Max Height: 8-12 metres

Growing Conditions

Clay Loam Sand

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

Position

Full sun Partial shade

Aspect: East–facing or North–facing or South–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: Sapindaceae
Native to GB/Ireland: No
Foliage: Deciduous
Habit: Bushy
Genus: Acer can be deciduous trees or large shrubs with paired, often palmately-lobed leaves and small flowers followed by characteristic winged fruits. Many have fine autumn colour, and some have ornamental stems
Name Status: Accepted

How to Grow

Cultivation

Grow in fertile, moist but well-drained neutral to acid soil in full sun or light shade. See tree cultivation for further advice

Propagation

Propagate by grafting in late winter or softwood cuttings in early summer

Suggested planting locations and garden types

Architectural
Wildlife gardens
Low Maintenance

Pruning

Pruning group 1, if necessary, from late autumn to midwinter only

Pests

May be susceptible to Acer gall mite, aphids, caterpillars and horse chestnut scale

Diseases

May be susceptible to Verticillium wilt, Acer leaf scorch and honey fungus