Hakea - Cultivation

Hakeas are excellent garden plants although some of the species native to Western Australia may be difficult to maintain for any length of time in areas of high summer humidity and rainfall (such as the eastern coastal strip of Australia). However, experience indicates that the western hakeas are more adaptable than western banksias and grevilleas in humid areas. In fact, Hakea is generally regarded as the hardiest genus of the Australian Proteaceae. Hakeas are useful for a number of purposes in the garden and the larger species, in particular, are excellent for screening. In addition, the flowers of all hakeas produce nectar and are excellent for attracting birds.

Proteoid roots   
Proteoid roots can often be seen by carefully removing a proteaceous plant from its pot, as shown here.
Photo: Brian Walters

Like most members of the Protea family, hakeas have a distinctive root system ("proteoid roots") consisting of tight groupings of many small "rootlets". These are believed to enable the plants to more efficiently take up nutrients from the nutrient-deficient soils where many of the species occur naturally. In cultivation this means that the plants can be adversely affected by fertilizers, particularly phosphorus. It is generally recommended that hakeas and other Proteaceae be fertilised only with low-phosphorus, slow-release fertilisers or not be fertilised at all.

Hakeas (in common with other Australian Proteaceae) perform best in well-drained soils and generally resent continually wet soils. Shallow clay soils can present problems but if garden beds are built up to 300-600mm, greater success is experienced. Hakeas are generally at their best in open, sunny positions although the plants will tolerate some shade but probably with reduced flowering.

Also in common with other Proteaceae, a number of Hakea species are susceptible to the root rot fungus, Phytophthora cinnamomi. The most dramatic effect of Phytophthora is the sudden demise in a matter of days of an apparently healthy plant. Improvement of soil drainage is the best means of minimising attack in areas where Phytophthora is known to exist.

Hakeas respond well to regular, annual pruning where about one-third of the plant is removed. This promotes branching and produces a plant with a bushy shape. Some plants can be cut back severly if they develop a "straggly" shape but others will not tolerate this treatment. If in doubt, always leave some green foliage on the plant.

There are few serious pests that attack hakeas. Borers may occasionally be a problem but will usually be noticed by the sawdust around the entrance to their tunnels. Inserting a piece of wire into the hole will often remove the pest, or the hole can be sealed with plastic wood. A variety of other pests such as caterpillars, sooty mould and scale may appear but they are no more of a problem on hakeas than on any other plant and can often be ignored, allowing natural control methods (eg birds) to operate. If treatment is necessary, conventional pest control methods are suitable.

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