Hoya is a genus of around 200 species with seven occurring in Australia. They are climbing plants with succulent foliage and the genus is popular in horticulture with numerous forms and cultivars being grown by enthusiasts. H.australis is the most widespread and the most commonly grown of the Australian species. There are four or five subspecies.
Hoya australis is a moderately vigorous climbing species. The leaves are thick and glossy and about 40-50 mm in diameter. The stems contain a white, milky sap. Flowers occur in clusters of up to 40, each on a long pedicel (stalk) and about 20 mm in diameter. They are borne on the same stalk in successive seasons and are fragrant, white in colour with deep red markings in the centre. Flowering is from late spring to summer. The seed pods are long and slender, about 100 mm long containing a number of seeds.
The species is popular in cultivation in tropical and subtropical areas and is successful in temperate areas if protected from frost (the species will tolerate light frosts). Good drainage is essential. H.australis is also suited to growing in containers and hanging baskets as it seems tolerant of root constraint. Flowering is best if good light is available but the plant will grow in reasonably heavy shade.
H.australis can be grown from fresh seed, which requires no pretreatment. Cuttings also strike readily.
Photo: Brian Walters