One of the exciting facts about Hoyas’ is that anyone can grow a Hoya plant; they are great indoor houseplant for beginners and expert gardeners. After Hoya Carnosa, Hoya australis is the next most famous plant in the Hoya species.
Hoyas’ have exceptional tolerance for neglect. The easy-to-care Hoya australis is excellent for any indoor space and does not require lots of water or maintenance. Choose a well-aerated, well-draining potting mixture and provide lots of sunlight during the active growing season.
In the wild, it mostly grows across the edge of rainforests, rocky areas and is famous because of its ability to attract butterflies. Hoya australis is now becoming a popular garden and houseplant because of its fragrant and showy white flowers.
This plant belongs to the Apocynaceae botanical family. It is long-lived and can grow to long lengths if left untrimmed. Other names for this plant include Waxvine, Honey plant, and Porcelain Flower. The waxy flowers on this grow in late winter and last well throughout summer.
Hoya australis was first collected by Europeans in 1770 on the northeastern coast of Australia. According to the Australian Native Plants Society, there are over 200 species of Hoya, and seven of them belong to Australia. Hoya australis is the most prevalent and commonly grown of the Australian species.
Continue reading to learn more about the beautiful Hoya australis plant. We have prepared a complete plant care guide in this article to assist you in growing this plant.
Table of Contents
Basic plant care for Hoya Australis
Hoya australis is a fast-growing climbing vine with trails up to 3m. It is an easy-to-care plant, and the air-purifying qualities make it a classic houseplant.
Choose a well-draining mixture for growing your Hoya australis. Aim for a soil medium that creates an epiphytic situation for the plant to grow.
Fast draining and well-aerated compost are essential for the plant to thrive. You can create your own mixture using 1 part (by volume) peat-free compost, 1 part orchid bark, and 1 part coarse perlite.
If you are planting in the succulent potting mixture or cactus compost, it is a good idea to amend the soil with perlite, charcoal, or pine bark.
A well-draining mixture will reduce overwatering damage and protect the plant from root-rot. The pH of the potting mixture should be ranging from 6.1 to 7.5, i.e., mildly acidic to neutral.
When grown in glass greenhouses, Hoya australis plant prefers a loam-based potting mixture with bark, sand, and leaf mold in equal parts. In such places, it is necessary to shade the plant from direct sunlight. You can increase the indoor humidity level in the greenhouse by keeping a water tank.
You can easily grow Hoya australis outdoors in USDA hardiness zone 10 and 11.
This plant has low to medium water requirements. The succulent leaves will store water, so on average, water the plant every 10 days.
Monitor the soil using a moisture meter or check it manually before watering the plant. It is crucial to allow the upper half of the potting mix to dry out between watering.
In summer, the soil should be moist and hydrated but not waterlogged. When watering a Hoya australis, thoroughly saturate the soil until water flows out of the bottom of the pot. Rainwater or filtered is best for watering, especially in areas with hard water.
In winter, you should water the plant sparingly. It is always better to underwater Hoya plants than overwatering them. If overwatered, the lower leaves will start yellowing and even fall off.
Hoya australis will easily indicate under-watering through its leaves. If the leaves get crinkly, your plant needs a drink. And don’t worry; the leaves will get back to their original form after a good watering session.
The majority of the cultivars grow epiphytically; therefore, Hoya australis prefers a drier root environment. It can tolerate a few weeks of drought but is usually sensitive to frost and cold weather.
Based on where Hoyas originate from- tropical climates and how they grow –by climbing up trees, they need bright, dappled sunlight for growing and blooming.
Just like several other Hoya plants, Hoya australis also needs bright but indirect light and embraces the sun all year round. It will also enjoy some early morning or late afternoon direct sunshine.
This plant needs full sun, but to protect it from sunburns, I would suggest keeping the plant a few feet away from direct sun. Intense direct sunlight will damage and burn the leaves. Never place your Hoya australis in a drafty window.
Choose a spot close to a window with the right combination of sunlight and shade to create optimum growth conditions.
Keeping in good light will help the Hoya plant to not only grow better but also prevents the soil from staying too damp. You can always readjust your plant’s position based on its growth and behavior.
Hoya Australis can survive in low light, but it is unlikely to bloom under such conditions. It does well under artificial light, making it a suitable plant for small office spaces or places with minimal sunlight.
Hoya australis is happy in indoor temperatures ranging from 18-24 degrees Celsius (65 – 75 o F) in summer and spring.Always avoid draughts and extreme temperatures because it will disturb the plant and hinder growth.
This plant prefers to be kept warm; therefore, the minimum room temperature should always be above 16 degrees Celsius. In winter, try to maintain the temp between 13-15 degrees Celsius (55 -60 oF).
In colder climates, always bring the plant indoors if the outdoor temperature, especially at night, is below 10 degrees Celsius.
Hoya australis are really diverse in their natural habitat;those coming from high elevation grow well in cooler nights.
Although Hoya Australis grows naturally in subtropical or tropical climates, it is now widely grown in different climates as an indoor plant. Therefore it is important to imitate the natural environment for healthy plant growth.
Hoya australis loves high humidity levels. However, it can also withstand low humidity levels with no harm, i.e., 40-60%.
To create a humid atmosphere, place the container on a gravel tray, expanded clay granules, or recycled lightweight aggregate. Keep the tray moist with water levels slightly lower than the gravel surface. Alternatively, you can also use a humidifier.
The growth rate depends on the Hoya species, but high humidity can really help accelerate growth.
You can apply any general-purpose fertilizer during the summer season. Hoya australis is a light feeder, so fertilize it with ¼ teaspoon of fertilizer per gallon of water once a month. Use balanced fertilizer like a 15-15-15 or a blooming fertilizer like a 7-9-5.
Hoya australis stops growing in winter, so discontinue feeding.
You can also add a good quality commercial plant nutrition solution to encourage growth for Hoya plants. It will increase the fertility of the potting mixture. Simply dilute 5ml (1 teaspoon) of nutrition per liter of water. Spray or mist the mixture over the plant foliage.
I would suggest feeding Hoya australis monthly spring through fall with a high-potassium liquid fertilizer diluted by half. Many gardeners highly recommend using an organic fertilizer biweekly instead of a chemical one.
With time the climbing vines of Hoya australis can reach 4 – 5 meters in height. If you are growing your Hoya plant in a container, it needs appropriate support and should be pruned back to maintain a bushy appearance.
You can prune the Hoya australis anytime when growth is excessive or after the flowering phase is complete. I would suggest pruning the plant in spring to maintain the desired length.
Blooms occur on the new growth, so over-pruning may slow down flowering. But some varieties will also bloom from old flower spurs, leaving them on when pruning will increase future blooms.
You can also treat the old mature plant with little pruning to rejuvenate the vine. While pruning, you can collect seeds from the plant. Let the pods dry then break them to collect the seeds. You cannot store these seeds for a long period of time, so it is better to sow them as soon as possible.
Propagation is the easiest method to expand the Hoya plant collection for enthusiasts. The two main approaches for Hoya australis are propagating in soil and water. The steps are explained in detail below:
Stem cuttings in soil
- The success of propagation relies on the cutting you choose. Therefore take a healthy non-flowering stem cutting in summer; choose a stem cutting with at least 2 nodes.
- Prepare a propagation mix of 3 parts perlite to 1 part coco peat or peat moss. And plant the cuttings in this potting mix.
- Use a propagator or a pot with a plastic cover to provide humidity and heat. The temperature should be at least 21 degrees Celsius (70 oF) or more.
- The roots will start within one month. You can also use rooting hormone and heat mats to improve the condition for propagation.
Stem cuttings in water
- Take a healthy cutting with at least two nodes. A node is a place where leaves appear and where the new leaves will grow on the cutting. This part should be submerged in water.
- Fill a propagation container with filtered water and add one or two drops of rooting hormone
- Now place the cutting in water and wait.
- Root buds will form in a week or two.
- Once few inches of the roots have developed, repot the cutting in soil.
- When transferring to soil keep the soil well-moist for the first week to help the roots assimilate to the new environment
Similar to other Hoyas, this one also prefers to stay root-bound. Do not repot Hoya australis until absolutely necessary as the plant dislikes root disturbance.
When repotting, choose a container with drainage holes and a well-draining potting mixture with plenty of perlite or pumice. Growing in a clay or terracotta pot will help maintain a healthy and robust root system.I always repot my Hoya plants in the spring season.
Hoya plants bloom in summer; they need to be well-established in the active growing season and, in some cases, stressed to start blooming.
The flowers have chocolate-vanilla sweet fragrance and appear in clusters up to 3 inches in diameter throughout the summer season. The flowers have a red spot at the base of each petal, and the coronas are reddish-purple. Under the right lighting conditions, the flowers can reach 10cm or 4 inches across.
Flowers grow in clusters of 40 on a long pedicel (stalk) and are approximately 2 cm in diameter. The long, slender seed pods are about 10 cm in length.
The stems of Australis are lined with pairs of succulent dark green leaves. The large leaves are 3–6 cm long and 2–5 cm wide. The succulent leaves are thick, fleshy, and oval, and the stems have white, milky sap.
Leaves grown in sunnier places are much more yellowish-green, whereas those growing in shadier areas are dark green.
Hoya australis is mostly grown in containers but can be trained to grow on trellises in verandahs, fences, and glasshouses. This evergreen climbing vine can reach 4–10 m (13–33 ft) in height.
Common Problems for Hoya Australis
The best strategy against pests is to prevent problems from developing in your houseplants. Mealybugs are the most common houseplant pest; almost every Hoya species is vulnerable to these pests. They can easily grow on your Hoyas in warm and humid conditions. Always keep your Hoya australis clean and free of dead leaves and kill the pests as soon as you see them.
Whiteflies are small sap-sucking insects that may infect your ornamental houseplants, especially during summer. They release sticky honeydew and cause the yellowing or even death of leaves. They become difficult to handle once populations are high.
Whiteflies mostly grow on the undersides of the leaves. They use their sharp, needlelike mouthparts to suck the sap from the phloem, which is the food-transporting tissue in the plant.
You can treat your plant with neem or horticultural oils to remove mealybugs and whiteflies, for large infestations use insecticidal soaps.
Snails and slugs are slimy creatures that can eat several leaves of your favorite plant in just one meal. They mostly appear in mild and moist weather. Holes in leaf edges and centers are a common sign of these pests. Slime trail on the plant stems and leaves are another indicator.
Spread Coffee grounds around plants you want to protect against slugs and snails. Diatomaceous earth is also effective against them. Copper is the best material for creating a barrier for them, just place a tape or strip of the copper around the pot. A combination of cultural, chemical, and biological measures is the most effective control for these two.
Yellowing leaves are another common problem with Hoya australis. It is typically caused due to cold temperatures, especially in cold climates during winter. Some other issues are leaf-drop, blackening of leaves, and dieback of stems. These may be due to poorly-drained or water-logged soil or even being too cold during the winter.
Fungal root-rot will occur as a result of overly wet or poorly drained soil. If your Hoya australis is severely damaged by root rot, the only way to save the plant is to take cuttings as soon as possible.
Sometimes this Hoya also suffers from wilting. It is caused by overwatering or over-fertilizing. It will restrain the roots from absorbing water due to the excessive levels of salts in the soil.
Tips for a Healthy Hoya Australis
- If your Hoya australis is not blooming, even under good light, try growing it with the little cooler temperature at night.
- The Hoyaaustralis flowers may produce drops of sticky nectar that can damage your furniture, so regularly check and clean the furniture near the plant.
- Mist the foliage with water, particularly if the plant is growing near central heating.
- With high humidity, the fungus can often be a problem, therefore always ensure good airflow.
- Misting will increase humidity and can keep away unwanted pests. But do not mist the leaves when the plant is in full bloom.
- When repotted, do not feed the plant for 5-6 weeks.
- In autumn and winter, Hoya plants are relatively dormant and need only moderate watering. Water your plant when the soil is fairly dry, but not dust dry.
- In the dormant phase, reduce the feeding to once a month until growth resumes in spring.
Hoya Australis varieties
The overall appearance of Hoya australis may vary depending on the subspecies you are growing. The majority of growers will curl the branches around a trellis or shelf to help the vine keep reaching new lengths. While some cut the vines down to a more manageable size to encourage more branching and vigorous growth on the plant.
Many subspecies and cultivars are available for Hoya australis, some of them are:
Hoya australis Tricolor: This climbing Hoya australis is native to northern Australia. The thick, oval waxy leaves feature splatters of color from white, pink, and green. This species will flower from one to three times per year.
Hoya australis Tenuipes: It has glossy round leaves that are thinner as compared to other Hoya australis subspecies. Therefore it requires more water than other Hoya australis. During warmer months, it gets clusters of white flowers with red centers. It can attract wildlife such as bees, butterflies, and hummingbirds.
Hoya australis ssp Australis Brookfield: The buds on this one are white-colored and bigger than those on Hoya Tenuipes. It has beautiful foliage with bronze colored new growth and golden colored veins.
Hoya australis Grande: It’s known for large foliage and the stunning cluster blooms that display a creamy star-shaped base with a small curl and hints of rose color under the inner star.
Hoya australis Lisa: This is variegated with creamy white, dark, and pale green leaves. The leaves are succulent but very thin. New growth produces beautiful shades of peach, red, and burgundy. This variety will grow slowly, but it’s extremely easy to care for.
Hoya australis Kapaho: It has glossy green leaves. New leaves on this one start pointy in shape, but as the plant matures, they get rounder.
Hoya australis Rupicola: It is a scrambler rather than a climber. The leaves are quite long and slender. The word rupicola means rock-loving; that is why this plant is found happily growing among rocks in the wild.
Hoya australis Oramicola: This will flower March through July, and the flowers are sweetly scented. The leaves are oval and get a lovely reddish tint in high light. This is a xerophytic plant, meaning that it is adapted to an arid climate and should be grown dry in the winter.
Frequently Asked Questions about Hoya Australis
Is Hoya Australis pet-friendly?
No, the Hoya Australis is not a pet-friendly plant. The sap of the plant contains latex, which is a skin irritant and is known to be toxic. Therefore keep the plant away from children and pets.
How to increase my chances of successful Hoya Australis propagation?
For successful propagation, place your cutting in a sealed environment such as a humidity dome, a plastic box, or a transparent plastic bag. A resealable freezer bag will also work well. This environment will keep the soil moist and increase the humidity levels, which in return, help your cutting to root faster.
Hoya Australis tops the list of Hoya plants for its fragrance, flower size, and robust growth. It’s a great indoor plant that can thrive under low light and dry conditions.
Depending on variety or cultivar, blooming is caused by environmental factors such as day length, light intensity, or cold night temperatures.
To conclude, Hoya Australis is easy-to-grow and often cold-tolerant, but it does better if protected from frost. With its moist succulent-like foliage and white flowers, it is a very appealing houseplant.