The Australian Tree Fern Makes a Big Impact

The Australian Tree fern is a fast-growing plant native to Australia. While better suited as an outdoor plant, due to its tall growth, Cyathea cooperi can be grown as an indoor floor plant provided it is given plenty of space. 

Australian Tree Fern

Australian Tree Fern Appearance

The Australian fern grows as a tree, reaching heights of 50 feet (9.2 meters) outdoors in its native habitat. As a houseplant, you can expect this fern to grow between 15 and 25 feet (4.6 to 7.6 meters) tall. The lacey fronds have a leathery texture and grow an impressive 10 to 20 feet (3 to 6 meters) long. The fern begins its growth by producing a wide crown, which then grows a single trunk covered in reddish-brown hairs. No blooms or berries are produced.

Australian Fern Light Requirements

Give your Australian Fern Tree filtered sunlight to avoid burning its foliage. A place, away from the window, in a bright, sunny room also works well. If the fern does receive a few hours of direct sunlight per day, ensure watering is increased to compensate.

Watering Your Australian Tree Fern

Watering Your Australian Tree Fern
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This fern is not drought tolerant, so ensure the soil remains moist at all times. Water your Australian fern once per week or when the soil of the surface feels dry. Avoid pouring water directly onto the fern’s crown, instead aim for the trunk of the plant. 

Soil and Fertilizer Requirements

Provide the fern with a well-draining, loamy soil, high in nutrients. Add a layer of mulch on top of the soil to provide the needed nutrients and help maintain soil moisture. Feed the Australian fern tree, during the spring and summer, with a liquid fertilizer. For small and medium-sized ferns, once per month is enough. For large plants, increase feedings to once every two weeks. 

Temperature and Humidity Levels

Like most ferns, the Australian Fern Tree prefers a warm and humid climate. Keep temperatures between 65 and 80 degrees Fahrenheit (18.3 to26.6 degrees Celsius). Moving your tree fern outdoors in the summer will promote growth but bring the plant back inside when temperatures begin to dip below 60 F(15.5 C). To provide enough humidity for your fern, fill a tray with small pebbles and water, placing it under the pot’s drip tray. Regular misting of the foliage is also recommended.

Propagating Your Australian Tree Fern

Propagating Your Australian Tree Fern
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Propagation only occurs by spores. To harvest the spores, place a piece of paper or small container under mature fronds and shake to release them. Sterilize a non-soil growing medium, such as vermiculite or peat by placing it in a heat-proof bowl and pouring boiling water over it. Let the soil sit to kill any bacteria, then drain the water and allow the medium to cool. Fill potting containers with the growing medium and sprinkle the spores onto the surface. Mist the growing medium, if dry, and cover the top of the pot with plastic. Place the pot in a spot with a consistent temperature of between 65 to 70 F (18.3 to 21 C) and mist the spores regularly to keep them moist. The spores will germinate in two to six weeks. Transfer the seedlings to their own pot once they reach two to three inches in height.

Common Pests and Diseases

The Australian Tree Fern is not often susceptible to pests but mealybugs and mites may appear if the plant is not healthy. If the infestation is small, remove the affected fronds. For larger infestations, first move the plant outdoors and spray the plant with a garden hose to dislodge the pests. If this is not successful, treat the fern with neem oil.

Crown rot is a result of pouring water directly onto the fern’s crown or water-logged soil. Signs of rot are yellowing and wilting fronds. The best course of action is to avoid the practices that cause the rot. When watering, pour the water onto the soil or stalk, avoiding the crown. Keep the soil moist, but ensure the soil drains and does not remain soggy. If crown rot is detected early, remove affected fronds and repot the fern in fresh soil. Apply a houseplant fungicide, as directed. 

The Australian Tree Fern is an impressive fern variety that makes a statement with its large size. This fern is a perfect choice for large spaces, such as foyers or large offices. The Tree Fern’s size also makes it a great focal point in a grouping surrounded by other easy-care indoor ferns.

Australian Tree Fern FAQ

When Should I Repot My Australian Tree Fern?

Repot your tree fern once a year to accommodate its growing size and refresh the soil. Once the fern has reached its mature size, stop repotting to control its size. 

Should I Prune My Australian Fern?

Remove dead or withered fronds to maintain the fern’s health.

Can I Grow My Australian Fern Tree Outdoors?

Yes, the fern will grow outdoors in USDA zones 8 to 11.

Is the Australian Tree Fern Considered Toxic?

While there is no evidence this particular fern is toxic, many fern species are, so precautions around pets and children should be taken.

What is the Annual Growth Rate of the Australian Tree Fern?

The tree fern has the fastest growth rate of the fern family at up to three feet (0.9 meters) per year.