Blackwood acacia
Acacia melanoxylon · Fabaceae
📷 Júlio Reis (Tintazul) · CC BY-SA 2.5
The gardener's calendar
In autumn, ease off feeding and take the chance to clean up around blackwood acacia and prepare for winter.
ID card
- Foliage
- Evergreen
- Flowering
- January to March (pale yellow clusters)
- Adult size
- 15 to 25 m tall, spreading form
- Growth
- Fast
- Hardiness
- Frost-tender (−5 to −8 °C depending on exposure)
- Origin
- Australia (New South Wales and Victoria)
- Soil
- Well-drained, tolerant to slightly acidic
Care
Sunlight
Plant it in full sun for optimal growth and abundant flowering. Acacia melanoxylon tolerates partial shade but produces fewer flowers and may become leggy. In cold climates, a south-east facing position protected from winter winds limits frost damage.
Watering
Water regularly during the first year after planting to encourage root establishment. Once established, this tree is very drought-tolerant. In humid regions, limit watering; in dry or Mediterranean climates, weekly watering during hot periods is generally sufficient.
Soil and planting
Prefer well-drained soil, as stagnant moisture causes root rot. Acacia melanoxylon accepts chalky, slightly acidic or neutral soils. Avoid waterlogged areas and enrich the planting hole with sand if the soil is heavy.
Pruning and maintenance
Pruning is not essential: the tree naturally adopts a harmonious form. Intervene after flowering (April-May) to remove dead, crossing or poorly oriented branches. Avoid severe pruning, which weakens the tree and slows recovery.
Fertilizer
No feeding is necessary once established, as this Acacia fixes nitrogen from the air thanks to its symbiotic roots. In very poor soil, a moderate application of balanced fertilizer in spring can support initial growth, but avoid excess.
Diseases and pests
This tree is generally robust. Watch for powdery mildew in humid, warm climates: improve air circulation through light pruning. Aphids and scale insects may affect young specimens in dry climates. Regularly check soil drainage to prevent root dieback, the main risk in very humid regions.
Did you know?
Acacia melanoxylon has been cultivated since the 19th century in the Mediterranean and Southern Europe for its hard, dense wood, used in fine cabinetmaking and carpentry. In Australia, its tannin-rich bark traditionally served to treat hides. Although introduced to Europe as an ornamental and timber species, it has become invasive in some Mediterranean regions.
Where to buy it
Best planted in autumn so the roots settle in before summer, or in early spring once the frost has passed. Pick a plant with healthy foliage and roots that are not exposed. Best time: March, October, November.
Add this plant to my garden →Plants from the same family
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Tips generated and checked by Viridia — adapt them to your local climate.