Indigofera australis

Austral Indigo

Indigofera australis Willd.

Austral Indigo (Indigofera australis) is a slender shrub of the Pea family found in all States, varying in size, habit and colour which is not surprising as it occurs over such a wide area. When growing wild in harsh conditions it is often straggly and leaning with few main stems, but with garden care it becomes a superior plant with beautiful sprays of blue-green foliage and dark purplish stems. These are seen at their best in a mixed border in contrast with other greens in a display of foliage.

The forms most commonly sold are perfectly frost hardy and also stand some drought, though adequate watering improves quality and prevents bare wood and dead branches. Its natural habit is upright, to 2 m high, with flexible stems tending to arch one way, but it can be trimmed lightly to make a strong and freely branched shrub. In certain soils, plants sometimes lean on the ground after loosening by storms, and interesting examples have been seen of such plants adapting themselves to nearly prostrate growth. Two such, after trimming, fanned out to cover 3 m across. It was considered that the appearance of these strong shrubs was improved as a result and it would seem that the species is suitable as a ground cover or as a specimen shrub if allowed to cascade down a slope.

Leaves are pinnate, openly spaced on the stems, around 10 cm long and velvety smooth to the touch. Their appearance is clean and fresh at all seasons, unblemished by pests and diseases, and their beautiful blue-green colour is most apparent during colder months.

Flower colour is unusual, ranging through soft purple hues, often pinkish and a change from other species flowering at the same time. The flowers are smooth, in short spires in the leaf axils, freely produced and showy, outlining the curves of the stems. They may open at any time from mid-September and may continue till November in a cool spring. After flowering the shrub is hung with shiny, bright-green pods ripening to produce squarish, hard seed. This is always plentiful and is the means by which young plants are raised. The seeds are hard and need soaking overnight in hot water before sowing. Most soils are suitable as long as they are free from lime, and with ordinary attention to watering the plants grow quickly after planting out and can be expected to have a fairly long life if protected from extreme drought. Most nurseries dealing in native plants stock this species. Only healthy specimens should be chosen as plants may not grow away from a check.

Based on text by Irene Beeton (1971)
 

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