A group of highly attractive, part-tender, evergreen trees and shrubs, that grow reasonably well outside in mild regions. In cooler areas they can be container-grown in a frost free conservatory or greenhouse.
Family: Fabaceae (legume, pea
Botanical Name: Acacia
Common Names: Mimosa, silver wattle, blue wattle
Foliage: Evergreen, finely divided, silvery or grey-green fern-like leaves.
Blossom: Spherical clusters of small, fragrant yellow flowers.
Flowering Period: Late winter to early spring.
Soil: Well-drained soil (sand or loam). Acid or neutral pH.
Conditions: Full sun. Best in a south or west facing aspect, in a sheltered location.
Type: Shrub or small tree.
Origin: Tasmania, Australia, Africa
Hardiness: Only hardy in coastal and mild areas of the UK (down to -5°C).
Best grown in full sun, in well-drained neutral to acid soil, in a sheltered situation. Acacias need plenty of sunlight throughout the year to thrive and flower well.
Suitable for growing outside in mild southwest regions of Britain. Provide winter protection in colder locations and grow against a warm south facing wall. Acacias can also be container grown and over-wintered in a cool, frost free, light environment such as a conservatory (ensuring a minimum temperature of 4°C (39°F)). Plant in a good neutral to acid soil-based compost, such as Ericaceous John Innes No. 2.
Protect plants in winter with a dry mulch. Provide further protection where temperatures fall below -5°C.
Feed in spring with an ericaceous, slow release plant food. Feed container grown plants fortnightly with a liquid feed from late spring to late summer.
Repot container grown plants every few years.
Lightly prune after flowering by cutting back straggly shoots. Also remove any dead, damaged and crossing branches.
Where necessary, large plants can be cut back after flowering by two thirds to restrict size.
Susceptible to honey fungus. Indoor grown trees can be affected by red spider mite, caterpillars and mealybugs.
Propagate from seed sown under glass in mid spring. Alternatively, take half-ripe heel cuttings and root in a propagator in early summer.
Acacia armata probably the best species for growing in containers. Flowers in early spring. Height to 10ft (3m) or more.
Acacia baileyana (cootamundra wattle) makes a graceful and leafy small tree. Height to 12ft (3.5m), spread 5ft (1.5m)
Acacia dealbata (mimosa) makes a splendid specimen tree in a warm sheltered spot. The young grey-green fern-like leaves are covered with silvery down. Tiny, fragrant yellow round flowers are borne in dense sprays in spring. Height to 25ft (8m), spread 10ft (3m) or more if conditions are good. For sale at You Garden.
Acacia pravissima (Oven's wattle) a graceful shrub with slender angular branches, covered with rich yellow flowers in spring. The leaf-like phyllodes are grey-green. Slow growing. Drought tolerant once established. Eventual height and spread to 20ft (6m).
Acacia retinodes has long willow like grey-green phyllodes (leaves) and large loose flower heads of pale yellow. Eventual height and spread to 20ft (6m). This variety is more tolerant of alkaline soil.