Acer palmatum 'Cosmos' (v)

RHS Plant Profile

Japanese maple 'Cosmos'

Trees

A hardy, compact vigorous deciduous tree to around 2.5m in height. Deeply lobed foliage and branches emerge bright coral pink in spring, changing to a softer pink with pink, white and green variegation, then finally to oranges and yellows in the autumn. The bark becomes pale yellow with maturity

Position

Full sun, Partial shade

Soil Types

Clay, Loam, Sand

Max Height

2.5-4 metres

Max Spread

2.5-4 metres

Size

Time to Maturity: 5–10 years
Max Spread: 2.5-4 metres
Max Height: 2.5-4 metres

Growing Conditions

Clay Loam Sand

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

Position

Full sun Partial shade

Aspect: East–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): 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: Unresolved

How to Grow

Cultivation

Grow in any moisture-retentive, well-drained soil in a sheltered position. Leaf colour is best in partial shade, although full sun can be tolerated if soil is reliably moist. Leaf scorch can be caused by lack of soil moisture or excessive exposure. See Japanese maples cultivation

Propagation

Propagate by softwood cuttings, layering or by grafting. Plants grown from seed are unlikely to come true, but may still be garden worthy

Suggested planting locations and garden types

City and courtyard gardens
Cottage and informal garden
Patio and container plants

Pruning

Pruning group 1, only from late autumn to mid-winter

Pests

May be susceptible to aphids and scale insects, including horse chestnut scale

Diseases

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