Australian Tree Fern Plant Profile

Tropical Giant Impressive, Challenging to Grow

Australian tree fern

Magnus Manske / Wikimedia Commons / CC BY-SA 3.0

Australian tree fern is more tree than fern. Usually, when we think of ferns, we picture plants such as painted ferns (Athyrium niponicum), which achieve a mature height of just 18 inches. But in its native habitat, the Australian tree fern grows to 40 feet or more. This tropical plant is easily too large for most indoor growing situations except for the largest of greenhouses.

Botanical Name Sphaeropteris cooperi, also known as Cyathea cooperi
Common Name Australian tree fern
Plant Type Evergreen fern
Mature Size 40 feet tall in its native environment
Sun Exposure Full shade is best
Soil Type Rich loam
Soil pH Not fussy about soil pH
Bloom Time Non-flowering; ferns are an ancient group of plants that reproduce via spores
Flower Color Non-flowering
Hardiness Zones 8 to 11
Native Area Australia

How to Grow Australian Tree Fern

Tree ferns thrive in mid-elevation tropical environments, where they can sometimes be found growing in great, prehistoric forests swathed in tepid mist. The key to growing a healthy tree fern is to provide ample humidity and consistency, avoiding extremes of heat, cold, and sunlight. The plant likes a temperature between 65 F and 80 F.

These plants are tolerant of salty winds near coastlines, but not salty soil conditions. Australian tree ferns do not acclimate well to rapid changes in humidity or temperature, which will result in browning leaves.

Light

Although these are shade-loving plants in general, they can also thrive in medium shade to full sun locations, whether exposed or sheltered.

Soil

Australian tree ferns can tolerate a variety of soil conditions including acidic soil, sand, loam, and clay, but they prefer a moist soil rich in humus.

Water

Keep the soil moist at all times. Australian tree ferns are not drought tolerant and need weekly watering, with high levels of moisture or humidity in dry weather. However, avoid watering the crown directly as this can cause rot. The less shade they get, the more water that they will need.

Fertilizer

During the growing season, feed with controlled-release fertilizer or biweekly with weak liquid fertilizer. Larger specimens are heavy feeders.

Propagation

Propagation happens via spores and is typically left to growers.

Repotting

Repot annually into larger pots with fresh, free-draining potting soil. When the plant reaches the maximum size allowed by the growing space, stop repotting to slow growth. Eventually, it will likely outgrow both the pot and the room.

Warning

Beware of the tiny hairs on the trunks of Australian tree fern, as they can be irritating to the skin.

Features of Australian Tree Fern

This majestic fern has curled fronds that emerge from the central leaf crown. The individual fronds generally reach four or five feet or as much as 20 feet in outdoor plantings. A well-grown tree fern is a fast-growing plant and will likely outgrow its space within a few years.

The trunk of the Australian tree fern starts out as a low, wide clump and spreads as much as six feet in a year before growing upward into a single slender trunk covered in glossy, ginger-brown hairs. The fronds are broad, bright green with triangular lacy leaves and a foliage spread of 8 to 15 feet. Its leaves do not change color in the fall, and there are no flowers or fruit. 

Varieties of Tree Ferns

The plant sold as an Australian tree fern is typically a Sphaeropteris (Cyathea) cooperi. There are, however, about one thousand different kinds of tree ferns, all found in tropical or subtropical settings. The New Zealand or Tasmanian tree fern is closely related, but the species is actually Dicksonia antarctica. This plant tends to have a narrower crown than the Australian tree fern but has similar growth requirements.

Where to Find Australian Tree Fern

This is one of the most commonly used tree ferns in the tropics. But unless you live in Australia or a similar region, you may have to go out of your way to view an Australian tree fern. These plants are grown mostly as large, potted ornamentals in the U.S. When they are grown outdoors, they are found mainly in public gardens and arboretums in tropical or semi-tropical zones. The plant has naturalized itself in Hawaii, where it is regarded as invasive due to its fast growth and prolific self-propagation.