The Rare Hoya Australis Is the Perfect Addition to Your Houseplant Collection

Hoya australis is a type of hoya plant known for its rounded, oval-shaped leaves, long climbing vines, and fragrant white flowers. Native to Australia, this vigorous hoya grows best with lots of bright, indirect light, well-drained soil, and water only when its soil feels dry.

Though hoya australis species is rarer than the similar hoya carnosa, you can purchase it from online sellers or specialty plant shops. There are some cultivars and several subspecies available, though many of the latter are harder to find in the US.

Hoya Australis Care

• Keep in a place with bright, indirect sunlight.
• Plant in loose, well-drained potting mix.
• Water when the soil has completely dried out.
• Fertilize monthly in spring and summer.

Light

Hoya australis prefers filtered or bright, indirect light. Keep the plant out of direct sunlight, which can burn its leaves. With sufficient light, however, new growth will take on a red tinge before it matures.

Soil

Plant hoya australis in a well-drained potting mix. You can purchase special mixes designed specifically for hoyas or make your own mix by combining two parts potting mix with one part perlite and one part orchid bark.

Water

As with other hoyas, the waxy, succulent leaves of hoya australis give this plant the ability to withstand relatively dry conditions, but sufficient water will support growth and blooms.

Water your plant when the soil has mostly dried out, but avoid letting leaves shrivel or wilt between waterings. Note that cultivars or subspecies with thicker leaves may need less frequent watering. Cut back on watering hoya australis in winter.

Temperature and Humidity

Hoya australis generally tolerates temperatures between 60°F and 95°F, though some subspecies can withstand temperatures over 95°F for extended periods without issue. This plant grows best with humidity levels between 50 and 60 percent but can adapt to drier indoor conditions around 30 to 40 percent humidity.

Fertilizer

Feed hoya australis with a balanced liquid houseplant fertilizer diluted to half strength during the growing season. It's common practice to stop fertilizing houseplants in regions with cold, dark winters, but some hoya growers swear by fertilizing less frequently and at lower levels through the winter.

Foliar sprays such as orchid mist can help encourage mature plants to bloom. During blooming, switch to a fertilizer with a higher proportion of phosphorous.

Types of Hoya Australis

• Hoya australis 'Lisa': A variegated cultivar with small, oval-shaped green leaves splashed with cream.
• Hoya australis ssp. oramicola: Known for smooth, glossy leaves with visible veins, vigorous growth, and loose, sweet-scented flowers.
• Hoya australis ssp. rupicola: Distinguished by narrow, pointed leaves, an upright growth habit, and large flower clusters.
• Hoya australis ssp. sanae: Has white flowers with pink centers and thick, waxy succulent leaves that make it particularly tolerant of dry conditions.
• H. australis ssp. tenuipes: Grows wide, round green leaves with visible veins and prolific, fragrant blooms.

Pruning

It's a good idea to prune hoya australis if growth becomes unwieldy or leggy. Prune after flowers have fallen away, and be sure to leave any peduncles, or flower stems, on the plant. Long, leggy vines or those that have lost their peduncles can be pruned away.

Cut back dead or damaged growth as it appears. Hoya australis may also benefit from a trellis or other structure to provide support for its climbing vines.

Propagating Hoya Australis

You can propagate hoya australis in soil or soilless mix using stem cuttings. You'll have the best chance of success in spring and summer when the plant is actively growing.

Before you begin, gather sterilized shears, small pots or containers, potting mix or perlite, and clear plastic bags or a clear plastic box. Here's how to propagate hoya australis.

1. Choose a healthy stem on the mother plant with at least two leaves at the tip and two leaf nodes along the stem. Make a diagonal cut just below a node, sterilizing your tools between cuts. Avoid taking cuttings from woody stems.
2. Fill small plant pots with potting mix or perlite, then spritz with water to moisten the growing medium and let it drain.
3. Plant the cuttings in the growing medium, ensuring the nodes on the lower end of the cutting are below the soil line.
4. Place the clear plastic bag around each container to hold in humidity, ensuring the cuttings aren't touching the plastic. You can also do this by putting the containers in a clear plastic box with the lid loosely closed. Open the plastic bag or box to let in fresh air every couple of days.
5. Put the cuttings in a warm place with bright, indirect light. Condensation on the sides of the plastic bag or box is a sign that the cuttings have enough moisture. Spray the growing medium with water as needed.
6. Roots should develop within 3-4 weeks. When the roots are about an inch long, you can repot the cuttings in soil and care for them as usual.

How to Grow Hoya Australis From Seed

You can also grow hoya australis from seed. You'll need a well-draining soilless seed starting mix, a flat or container with drainage holes, and a clear plastic bag or box with a lid.

1. Fill the container or flat with soilless mix.
2. Sow the hoya australis seeds over the surface, then cover them with a thin layer of soilless mix.
3. Spritz the surface with water to moisten it.
4. Seal the container in a plastic bag or put it in a plastic box with the lid lightly closed.
5. Put the bag or box in a warm place with bright light.

You should see germination in about a week, and seedlings can be potted up in about a month.

Potting and Repotting Hoya Australis

Hoyas have delicate root systems, so they must be repotted carefully. Repot in the spring or summer when the plant is actively growing, and water a day or two before you plan to repot. Use a container that's only an inch or two larger across than the previous pot. Rather than loosening the roots while repotting, keep the root ball intact.

Add fresh soil to the bottom of the new pot, place the root ball in the container, and fill in with fresh soil. Use a pot with adequate drainage holes. Terra cotta pots may help avoid overwatering, as they wick away excess moisture.

Common Pests & Plant Diseases

Common houseplant pests like aphids, thrips, and mealybugs can infest hoya australis plants, sucking the sap from their succulent leaves. Keep an eye out for gray spots on leaves, which can be a sign of botrytis blight, a fungal infection.  

How to Get Hoya Australis to Bloom

Hoya australis can take anywhere from a few years to several years to mature enough to bloom. However, mature plants can benefit from consistent watering, lots of indirect light, and fertilizer high in phosphorus.

How Long Does Hoya Australis Bloom?

Once they've fully opened, you can expect hoya australis flowers to last for about a week before they fade.

What Do Hoya Australis Flowers Look and Smell Like?

Hoya australis blooms with clusters of tiny white star-shaped flowers with red centers. The fragrant flowers are known for their sweet scent reminiscent of honey, vanilla, or chocolate.

How to Encourage More Blooms

Give your plant plenty of bright, indirect light, and consider using a grow light in regions with cold, dark winters. Water consistently, avoiding stressing the plant with dry conditions between waterings. Using a fertilizer with a higher ratio of phosphorus can also help hoya australis bloom.

Deadheading Hoya Australis Flowers

Allow faded flowers to drop off naturally rather than deadheading. Never prune away portions of stem with peduncles because flowers will grow from those same structures the next time your plant blooms.

Common Problems With Hoya Australis

Leaves Turning Yellow

Yellowing leaves are a common sign of overwatering. They can also indicate a lack of light. Check the soil moisture—if the soil is soggy and you've been watering frequently, stop watering and wait until the soil has completely dried out before watering again.

Consider switching your plant to a terra cotta pot, which can help prevent overwatering. If the plant is etiolated and reaching for the light source, it may need more light. Move it closer to the window or grow light.

Brown Spots on Leaves

Brown spots on the leaves of hoya australis can indicate leaf spot, a fungal disease typically caused by overwatering. Remove affected leaves with clean pruners, sterilizing them with rubbing alcohol between each cut, and treat the plant with an organic fungicide.

Shriveled Leaves

Shriveled, wrinkled, or wilted leaves often indicate a severe lack of water. Give your plant a deep watering, monitor the soil moisture regularly, and get on a consistent watering schedule to prevent stressing the plant in the future.