Black acacia
Acacia decurrens · Fabaceae
📷 J Brew · CC BY-SA 2.0
The gardener's calendar
In autumn, ease off feeding and take the chance to clean up around black acacia and prepare for winter.
ID card
- Foliage
- Evergreen, finely divided (bipinnate)
- Flowering
- Winter to spring (January-April), golden yellow flowers in clusters
- Mature size
- 8 to 12 m tall, 6 to 8 m spread
- Growth rate
- Fast
- Hardiness
- Tender (-5 to -8 °C max)
- Origin
- Australia (New South Wales)
- Soil type
- Well-drained, light, tolerates poor soils
Care
Sunlight
Plant your black acacia in full sun for optimal growth and abundant flowering. It tolerates shade poorly. In cold regions, prefer a location sheltered from winter winds to minimize frost damage.
Watering
Water regularly after planting until fully established (2-3 years). Once mature, black acacia is very drought-tolerant thanks to its deep root system. Reduce watering in winter, except during exceptional drought.
Soil and drainage
Install your acacia in well-drained soil, as it fears waterlogging and heavy soils. Sandy or gravelly soil, even if low in fertility, suits it perfectly. Improve drainage if necessary at planting time.
Pruning and shaping
Perform light pruning after flowering to remove dead or poorly oriented branches and balance the shape. Avoid severe pruning as it can weaken the tree. The natural form is generally upright and requires only minor maintenance.
Fertilizing
As a legume, black acacia fixes atmospheric nitrogen and requires little nutritional input. Apply balanced fertilizer or light amendment in spring during the first years, then gradually cease once the tree is established.
Diseases and pests
Black acacia is generally robust. Watch for scale insects and psyllids in hot, dry conditions. Excess moisture can promote fungal diseases: ensure good air circulation and correct drainage. Young plants are sensitive to frost and late frosts.
Did you know?
Black acacia is historically known for having supplied gum arabic exploited on a large scale in the 19th century, though this production is associated with other species. In Australia, its tannin-rich bark long served for dyeing and leather tanning, while today it is planted throughout the Mediterranean basin as a valuable ornamental tree for its spectacular winter yellow flowering.
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
- Chinese wisteriaWisteria sinensis
- Common broomCytisus scoparius
- Black locustRobinia pseudoacacia
- Common PeaLathyrus oleraceus
- Honey locustGleditsia triacanthos
- Hairy greenweedGenista pilosa
Tips generated and checked by Viridia — adapt them to your local climate.