Acacia - Cultivation

Spoiled for Choice

There are over 900 species of Acacia that are native to Australia and, although only a fraction of that number are readily available, selecting suitable species for any given situation rarely presents a problem. Acacias are often regarded as being quick growing but short lived and to a certain extent this is true but they are particularly useful for providing quick growth to cover the stark, empty look of a new garden. Most should live from 12 to 15 years in suitable conditions but many will last much longer.

The accompanying table lists 20 wattles, most of which are suited to temperate areas unless otherwise indicated. The majority should be reasonably easy to obtain. Of course, you can always grow your own plants if particular species prove difficult to obtain - see the Acacia propagation section.

A few species of Australian acacias have proved to be weed pests both in Australia and in other parts of the world. In South Africa, for example, A.saligna, A.cyclops, A.melanoxylon, A.mearnsii, and A.decurrens cause serious problems and no natural predators exist to keep them under control. Within Australia, A.paradoxa has been reported as being a problem in parts of Victoria and even the popular Cootamundra wattle (A.baileyana), Queensland silver wattle (A.podalyriifolia) and golden wreath wattle (A.saligna) are weeds of the Sydney bush and other areas. These species should not be planted in gardens in the vicinity of natural bushland. These and other problem species are listed in our Environmental Weeds section.

Species	Common Name	Size HxW (m)	Flowering Period	Flower Colour	Comments
A.adunca	Wallangarra wattle	5 x 3	Wi/Sp	Yellow	Sunny, well drained location.
A.amblygona Prostrate	None	0.3 x 1.5	Wi/Sp	Gold	Sunny, open position. Excellent in a rockery.
A.boormanii	Snowy River wattle	4 x 3	Wi/Sp	Yellow	Attractive greyish foliage. Best in cold climate.
A.buxifolia	Box-leaf wattle	3 x 2.5	Wi/Sp	Yellow	Hardy in sun and semi-shade and withstands extended dry conditions.
A.cognata	Bower wattle	6 x 5	Wi/Sp	Lemon	Numerous small growing cultivars now available which look wonderful in large containers (eg. 'Bower Beauty', 'Limelight', 'River Cascade' 'Waterfall'.
A.conferta	None	2 x 2	Au/Wi	Gold	Small grey-green phyllodes. Flowers in globular heads on long stalks.
A.cultriformis	Knife-leaf wattle	4 x 3	Sp	Yellow	Small blue/grey phyllodes with a triangular shape. Graceful growth habit.
A.elongata	Swamp wattle	2 x 2	Wi/Sp	Yellow	Erect growth habit. Tolerates poor drainage.
A.fimbriata	Fringed wattle	5 x 3	Wi/Sp	Gold	Dense, attractive foliage with lightly scented flowers. Small forms available.
A.flexifolia	Bent-leaf wattle	1.5 x 1.5	Wi	Lemon	Small, attractive shrub for many areas. Withstands extended dry periods.
A.glaucescens	Coast Myall	10 x 8	Wi/Sp	Yellow	Very attractive tree with ornamental blue/grey foliage.
A.leprosa 'Scarlet Blaze'	Cinnamon wattle	5 x 3	Wi/Sp	Orange/red	Red flowers are unusual in Acacia. Best for areas of low humidity.
A.merinthophora	None	3 x 2.5	Wi/Sp	Yellow	Unusual long, narrow phyllodes. Best for areas of low humidity.
A.myrtifolia	Myrtle wattle	1.5 x 1.5	Wi/Sp	Cream	Attractive small species with reddish stems that contrast well with the pale flower clusters.
A.oxycedrus	Spike wattle	5 x 3	Wi/Sp	Lemon	Very, very ornamental but very, very prickly!
A.pravissima	Ovens wattle	4 x 3	Wi/Sp	Gold	Very ornamental. At least one prostrate form is available ('Golden carpet') that makes an unusual groundcover.
A.pulchella	Western prickly Moses	1.5 x 1.5	Wi/Sp	Gold	Mainly for areas of low humidity. Very ornamental with ferny foliage.
A.spactabilis	Mudgee wattle	4 x 2.5	Wi/Sp	Yellow	One of the most 'spectacular'! Beautiful ferny foliage.
A.terminalis	Sunshine wattle	2 x 1.5	Au/Wi/Sp	Lemon to Gold	Attractive plant with ferny foliage. Variable flower colour.
A.vestita	Hairy wattle	4 x 3	Sp	Gold	Attractive, weeping growth habit. Requires watering during extended dry periods.

Maintenance of wattles in the garden is fairly straight forward and should not involve much more than a light pruning to shape the plant in its early years and an occasional application of fertilizer, preferably of a slow-release type. Most wattles will not recover from a severe pruning so always ensure there is green foliage below any cut.

Borers

	Borer attack on Acacia parramattensis Photo: Brian Walters

Everyone knows that wattles are susceptible to borers, don't they? It's just a fact of life.

But are they?

Borers mainly affect some of the tree species, particularly those in the "Black wattle" group which includes A.decurrens, A.parramattensis and A.mearnsii. These trees often grow very rapidly but then deteriorate after 7-8 years as the damage inflicted by borers becomes more than the plant can cope with. By the time the tree dies, it is often very large and spreading and difficult to remove safely. This group is probably not ideal for small suburban gardens. Not all large wattles are subject to borer attack. Acacia elata (Cedar Wattle), for example, is a magnificent tree which is very long lived although perhaps too large for all but very large gardens.

Many of the smaller wattles are probably no more susceptible to borers than other garden plants and control, if needed can be readily achieved by skewering the pest with a wire inserted into the hole in the trunk or branch.

Acacias and Allergies

Wattles have been widely accused of causing hay fever. But does this stack up to scrutiny?

There is no doubt that some people are allergic to Acacia pollen but there is also no doubt that many allergies attributed to wattles are, most likely, caused by pollen from grasses and other plants that happen to be flowering at the same time.

The general consensus among researchers seems to be that the pollen of wattles is relatively heavy and is not carried long distances by breezes. The Australasian Society of Clinical Immunology and Allergy (ASCIA) has this to say:

"Wattle is frequently blamed for early spring symptoms but allergy tests (skin prick tests) seldom confirm that wattle is the true culprit."

Furthermore, as reported in ANPSA's Acacia Study Group newsletter, there has been a recent, detailed study on the subject allergic rhinitis ('hay fever') in Australia by the Australian Institute of Health and Welfare (an Australian Government Agency).

The 48 page report covers matters such as the causes of allergic rhinitis, its prevalence within the Australian community and management of the problem. Various causes are discussed, including sensitivity to pollen. In this regard, the report notes that "the tiny, hardly visible pollens of wind-pollinated plants are the predominant triggers." The report also states that "pollens of insect-pollinated plants (such as Australian wattles) are too heavy to remain airborne and pose little risk".

Some particular pollens to which sufferers are commonly allergic are listed, and these include grasses, some flowering plants such as pellitory weed, Patterson's curse, ragweed and parthenium weed, and some trees such as silver birch, olive tree, English oak, and Murray pine.

Reference: Australian Institute of Health and Welfare 2011. Allergic rhinitis ('hay fever') in Australia. Cat. No. ACM23. Canberra: AIHW

The report can be downloaded in full from the Australian Institute of Health and Welfare's web site.

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