Jonathan Ya'akobi

Grevillea – Fine Landscape Garden Plants for a Dry Climate

Grevillea shrubs are not the easiest landscape garden plants to grow, but their immense ornamental value, combined with their tolerance of drought, make them vital ingredients in the dry climate gardener’s cookbook.

Grevilleas are woody, evergreen plants from Australia, including a large number of species and garden varieties, ranging from tall trees and large bushes, to low-growing sprawling shrubs. Usually they have a very distinctive leaf shape that gives the foliage a fine, feathery texture, and the long, slender flowers, typical of the Proteaceae botanical family.

In addition to being garden plants of much ornamental value, their great merit is in their modest water requirements. In near-desert climates that receive only 250 mm of rainfall a year, Grevilleas can be grown on as little as 200 mm per year. In temperate Mediterranean climates that receive some 400 mm a year, established plants can get through the summer with virtually no additional irrigation. This makes them essential plants at the disposal of the dry climate gardener.

Due to their fine foliage texture, Grevillea shrubs are most suited, stylistically speaking, to Mediterranean gardens and in association with plants of similar leaf size and shape. They combine beautifully with types of Juniper, Melaleuca, Pistachio, Leucophyllum, as well as Rosemary, Lavender, and shrubby Chrysanthemums, to name but a few examples. They are especially appropriate with other ornamental Proteas, such as Banksia and Hakea.

On the other hand, they look out of place with large-leaved, course textured plants, and so are unsuited to tropical style compositions. A specimen, rather like an ingredient in a cooked dish, is only as good as its place in the scheme of things.

Growing Conditions

Despite being hardy to drought and to the lowest temperatures that a Mediterranean climate is likely to reach, Grevilleas are not entirely easy to grow. They are very sensitive to poor drainage, and are liable to degenerate under conditions of frequent, shallow watering. Many species are intolerant of high salt levels in the soil, a condition that is all too prevalent in dry climates. For this reason, occasional, deep irrigation is necessary to leach excessive salts from the soil.

Like other genera belonging to the protea family, they suffer from excessive levels of phosphorous present in the soil. It is best therefore to avoid applying chemical fertilizers, or at least those high in phosphorous. This is yet another argument against the use of automatic fertilizer pumps, which consistently add to the soil, salts in general and phosphorous in particular. On the hand, Grevilleas tend to be sensitive to root disturbance, so digging in compost around the plants should be exercised with great care.

Despite these drawbacks, as well as a fairly high mortality rate amongst new plants, the various trees, shrubs and ground covers belonging to the genus Grevillea, are too valuable as ornamental landscape plants, and too useful as water-conserving plants, for the gardener in a dry climate to ignore.

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