Acacia melanoxylon

RHS Plant Profile

Australian blackwood

Other common names

blackwood, blackwood acacia, Tasmanian lightwood

Synonyms

Acacia arcuata

Trees

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A graceful evergreen tree possibly reaching 12m. Its 'leaves' are leathery grey-green and variable in shape. Some are ferny in shape with a slender stem, some have a saml leaf where the stem is flattened, but generally they are just the leaf stem alone, flattend into a 'leaf' longer than they are wide with a slight curve. In spring, the flowers are clouds of small, fluffy white to pale yellow flowers which may develop into 10cm brown, twisted-ribbon seed pods. The bark is grey with dark fissures

Position

Full sun

Soil Types

Loam, Sand

Max Height

8-12 metres

Max Spread

4-8 metres

Size

Time to Maturity: 10–20 years
Max Spread: 4-8 metres
Max Height: 8-12 metres

Growing Conditions

Loam Sand

Moisture: Well–drained
pH: Acid or Neutral

Position

Full sun

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): H3
Drought Resistance: Yes

Colour & Scent

Season	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family: Fabaceae
Native to GB/Ireland: No
Foliage: Evergreen
Habit: Spreading branched
Genus: Acacia can be deciduous or evergreen trees, shrubs or climbers, with alternate, pinnately divided leaves or simple modified leaf-like stalks (phyllodes), and tiny, sometimes fragrant, flowers in short spikes, or in racemes or spikes of spherical heads
Name Status: Correct
Plant Range: S Australia

How to Grow

Cultivation

Grow outdoors in neutral to acid well-drained soil in sheltered location with full sun. Suits courtyard and urban gardens in milder locations, but will need winter protection elsewhere. Under glass, grow in peat-free, ericaceous or loam-based compost in full light. Resents hard pruning. For more advice see tree cultivation

Propagation

Propagate by semi-ripe cuttings or seed. For advice see propagation from seed (tree/shrub

Suggested planting locations and garden types

Architectural
City and courtyard gardens
Gravel garden
Mediterranean climate plants

Pruning

Pruning group 8

Pests

May be susceptible to glasshouse red spider mite, fluted scale and mealybugs

Diseases

May be susceptible to honey fungus