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Samoan waxplant (Hoya australis)

Hoya australis is an evergreen perennial with succulent climbing vines that often twine, and it may also grow as a trailing, creeping, or semi-shrubby plant; in its native habitat it can grow as an epiphyte.

LightSources differ on light recommendations: bright conditions favor flowering, with bright filtered light suggested indoors, while other guidance recommends full sun or some dappled shade and avoiding the strongest direct s
WaterUse a well-drained medium; during the growing season, water thoroughly while avoiding overwatering or waterlogging, water again after the surface dries, and keep it drier and only slightly moist in winter.
HumidityIt is reported to prefer high humidity.
TemperatureA single source gives conflicting hardiness-zone information within its own account. It is reported to be frost tender; keep above freezing.
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Overview

Hoya australis is an evergreen perennial with succulent climbing vines that often twine, and it may also grow as a trailing, creeping, or semi-shrubby plant; in its native habitat it can grow as an epiphyte.

Origin and habitat

Sources differ on its native range, which includes northern and eastern Australia, New Guinea, and parts of the southwestern Pacific and Melanesia; some accounts also include Indonesia, Sabah in Malaysia, Fiji, New Caledonia, the Solomon Islands, Samoa, Tonga, and Vanuatu, with the range varying according to subspecies treatment. It occurs along tropical rainforest margins, in rocky areas, coastal scrub, sea cliffs, mangrove margins, and native forest, and may grow as an epiphytic vine climbing other plants. It is mainly adapted to humid tropical to subtropical environments and is especially common in low-elevation tropical areas.

Characteristics

Sources differ on mature height, reported at about 400–1000 cm, while a single source reports a mature spread of about 100–150 cm. It grows vigorously and can grow rapidly as a houseplant, and it may flower earlier than some other Hoya. The opposite, simple leaves are thick and succulent to leathery, often glossy, and range from elliptical or oblong to ovate or nearly round; they may become yellow-green in stronger light and darker green in shade. The fleshy, waxy flowers are white to creamy white with red to dark-red markings at the center or base of the corolla, usually star-shaped and clustered, with a strong sweet fragrance and abundant nectar; sources differ on flowering season, while the fruit is a slender, spindle-shaped follicle containing wind-dispersed seeds with long tufts of hair.

Light

Sources differ on light recommendations: bright conditions favor flowering, with bright filtered light suggested indoors, while other guidance recommends full sun or some dappled shade and avoiding the strongest direct sunlight in hot areas.

Watering

Use a well-drained medium; during the growing season, water thoroughly while avoiding overwatering or waterlogging, water again after the surface dries, and keep it drier and only slightly moist in winter.

Humidity and airflow

It is reported to prefer high humidity.

Temperature and dormancy

A single source gives conflicting hardiness-zone information within its own account. It is reported to be frost tender; keep above freezing.

Growing medium and mounting

It requires a well-drained medium; loam or sandy soil can be used, while indoors a well-drained potting mix is suitable. It tolerates acidic, neutral, and alkaline conditions, and some sources favor humus-rich, fertile soil that retains an appropriate amount of moisture.

Propagation

Hoya australis can be propagated by cuttings, semi-ripe cuttings, layering, or seed.

Common problems

Common pests include aphids, mealybugs, scale insects, spider mites, and greenhouse whiteflies. Disease problems are generally limited, but overwatering or waterlogging can lead to root rot, while insufficient light may reduce optimal flowering. It is sensitive to frost and temperatures below freezing, so in cold regions it needs to be moved indoors or given cold protection.

Identification

Hoya australis is distinguished by thick, succulent to leathery leaves, twining vine-like stems, and clusters of waxy, fragrant, white to creamy-white star-shaped flowers that commonly have red markings at the center.

Photos

Hoya australis
📷 Tauʻolunga · CC BY-SA 3.0 · source
Hoya australis
📷 Greg Tasney, some rights reserved (CC BY-SA), uploaded by Gr · CC BY-SA · source
Hoya australis
📷 no rights reserved, uploaded by Tim Shields · CC0 · source

Sources