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

Hoya australis is a variety of hoya plant known for its round oval leaves, long vines, and fragrant white flowers. Native to Australia, this vigorous hoya grows best in plenty of bright indirect light, well-drained soil, and watering only when the soil is dry.

Although Hoya southern is less common than the similar Hoya carnosa, it can be purchased from online sellers or specialty plant stores. Several cultivars and several subspecies are available, although many of the latter are more difficult to find in the United States.

Hoya Australis Care

Light
Hoya australis prefers filtered or bright indirect light. Keep the plant out of direct sunlight as it can burn the leaves. However, given sufficient light, new shoots will turn red before reaching maturity.

Earth
Plant southern hoya in a well-drained potting mix. You can buy a special mixture designed specifically for hoyas, or make your own by mixing two parts potting mix with one part perlite and one part orchid bark.

Water
As with other hoyas, Hoya southern’s succulent, waxy leaves give this plant the ability to tolerate relatively dry conditions, but sufficient water will promote growth and flowering.

Water the plant when the soil is mostly dry, but do not allow the leaves to wilt or wilt between waterings. Note that varieties or subspecies with thicker leaves may need less frequent watering. Reduce watering of hoya in southern winter.

Temperature and humidity
Hoya australis typically tolerates temperatures between 60°F and 95°F, although some subspecies can tolerate temperatures above 95°F for extended periods of time without issue. This plant grows best in 50 to 60 percent humidity, but can adapt to drier indoor conditions with 30 to 40 percent humidity.

Fertilizers
During the growing season, feed Hoya southern with a balanced houseplant fertilizer diluted by half. In regions with cold, dark winters, fertilizing houseplants is usually stopped, but some Hoya growers recommend fertilizing less frequently and in smaller quantities during the winter.

Foliar sprays, such as orchid sprays, can help encourage mature plants to bloom. During flowering, switch to fertilizers with a higher percentage of phosphorus.

Hoya australis species

Hoya australis ‘Lisa’: A variegated variety with small oval green leaves tinged with cream.
Hoya australis subsp. oramicola: Known for its smooth, shiny leaves with prominent veins, vigorous growth and loose, sweet-smelling flowers.
Hoya australis subsp. rupicola: Characterized by narrow, pointed leaves, erect growth and large inflorescences.
Hoya australis subsp. Sanae: has white flowers with pink centers and thick, succulent, waxy leaves, making it particularly tolerant of dry conditions.
H. australis subsp. tenuipes: The tree grows widely, has round green leaves, prominent veins and abundant fragrant flowers.

Cut
You should prune your southern hoya if the plant’s growth becomes unwieldy or prolonged. Prune after the flowers have fallen and be sure to leave flower stalks or stems on the plant. Long, leggy vines or vines with missing stems can be pruned.

Trim dead or damaged shoots as they appear. Hoya australis can also benefit from a trellis or other structure to support its vines.

Hoya Australis propaganda
Southern Hoya can be propagated in soil or soilless mixture by cuttings. You will have the greatest chance of success in the spring and summer, when the tree is actively growing.

Before you begin, prepare sterilized scissors, a small pot or container, potting mix or perlite, and a clear plastic bag or clear plastic container. Here’s how to propagate southern hoya.

Select a healthy stem from the mother plant with at least two leaves at the top and two segments of leaves along the stem. Make a diagonal cut just below the button, sterilizing the tools between cuts. Do not remove branches from tree trunks.
Pour potting mix or perlite into small plant pots, then mist with water to moisten the growing medium and allow to drain.
Plant the cuttings in the growing medium, making sure that the nodes at the bottom end of the cuttings are below the soil line.
Place clear plastic bags around each container to retain moisture, making sure the cuttings do not touch the plastic. You can also do this by placing the container in a clear plastic box with a tight-fitting lid. Open the plastic bag or box every few days to provide fresh air.
Place the cuttings in a warm place with indirect light. Condensation on the walls of the bag or plastic box is a sign that the cuttings are quite wet. If necessary, spray the growing medium with water.
Roots will develop within 3-4 weeks. Once the roots are about 1 inch long, you can transplant the cuttings into soil and care for them as usual.

How to Grow Hoya Australis From Seed

You can also grow southern hoya from seeds. You will need a soilless potting mix that drains well, a flat container or container with drainage holes, and a clear plastic bag or box with a lid.

Fill a container or flat surface with waterproof mixture.
Sow southern hoya seeds onto the surface, then cover with a thin layer of soilless mixture.
Spray water on the surface to dampen it.
Seal the container in a plastic bag or place it in a plastic container with a tight-fitting lid.
Place the bag or box in a warm, well-lit area.
In about a week you will see germination, and after about a month the seedlings can be planted in pots.

Planting and replanting Hoya Australis
Hoyas have a delicate root system, so they should be replanted carefully. Repot in spring or summer when the plant is actively growing, and water a day or two before planning to replant. Use a container that is just an inch or two larger in diameter than the previous pot. Instead of weakening the roots during repotting, leave the root ball intact.

Fill the bottom of the new pot with fresh soil, place the root ball in the container and cover with fresh soil. Use a pot with enough drainage holes. Terracotta pots can help prevent overwatering as they remove excess moisture.
Common plant pests and diseases
Common houseplant pests such as aphids, thrips and mealybugs can attack Hoya australis plants by sucking the sap from their succulent leaves. Keep an eye out for gray spots on the leaves: this could be a sign of leaf damage or a fungal infection.

How to make southern hoya bloom?
Hoya australis can take a few to several years to mature and bloom. However, mature plants may benefit from regular watering, plenty of indirect light, and high-phosphorus fertilizer.
How long does Hoya Australis bloom?
Once they are in full bloom, you can expect Hoya australis flowers to last about a week before wilting.

What does a Hoya Australis flower look and smell like?
Hoya southerna blooms with clusters of small white star-shaped flowers with a red center. The fragrant flowers are known for their sweet scent, reminiscent of honey, vanilla or chocolate.

How to stimulate more flowers
Provide your plants with plenty of bright, indirect light and consider using grow lights in regions with cold, dark winters. Water constantly, avoiding stressing the plant in dry conditions between waterings. Using fertilizers with a higher percentage of phosphorus can also encourage southern hoya to bloom.

Deadly Hoya Australis flower
Let the wilted flowers fall naturally rather than wither. Never prune the stems, because the next time your plant blooms, flowers will grow from the same structures.
Common problems with Hoya Australis
Leaves turn yellow
Yellow leaves are a common sign of overwatering. They may also indicate a lack of light. Check soil moisture: If the soil is damp and you water frequently, stop watering and wait until the soil is completely dry before watering again.

Consider repotting the plant in a terracotta pot to prevent overwatering. If the plant is losing its leaves and reaching towards the light source, it may need more light. Move it closer to a window or plant it in a bright place.

Brown spots on leaves
Brown spots on Hoya southern leaves may be a sign of leaf spot, a fungal disease often caused by overwatering. Remove affected leaves with clean pruning shears, sterilize them with alcohol between each cut, and treat the plant with an organic fungicide.

Wilting leaves
Wilted, shriveled or wilted leaves are often a sign of severe water deficiency. Water the plant deeply, regularly monitor soil moisture, and establish a consistent watering schedule to avoid stressing the plant in the future.