Rough Tree Fern

Rough Tree Fern (Cyathea australis) is the hardiest of the Australian tree ferns and the one to plant for a rainforest canopy in a suburban garden. Given time it builds a trunk to about 5m with a crown spreading 3m across, though that takes fifteen years or more, so most gardens enjoy it at head height first.

Why you'll love it

• Tougher than it looks. It handles frost, wind, humidity and wet feet, a rare combination in a fern and the reason it succeeds where soft tree ferns sulk.
• Instant rainforest structure. A single trunk with a 3m crown creates a canopy layer in one plant.
• Evergreen, despite appearances. It holds its fronds year round, so the garden does not go bare in winter.
• It suits a shaded courtyard. Slow growth and a narrow footprint make it one of the few canopy plants for a small garden or a large pot.

Where it works best

Feature planting. One fern in a shaded corner does more than a bed of shrubs. Underplant with clivias or native violet so the trunk stands clear as it gains height.

Small and shaded gardens. Narrow side gardens, courtyards and the southern side of a house all suit it. Allow about 3m of clear width for the mature crown.

Pots and containers. It grows well in a pot at least 500mm wide, the practical option on a shaded balcony, though a potted tree fern dries out far faster than one in the ground.

Growing Rough Tree Fern in Australia

Position and climate. Part shade is ideal, with protection from hot afternoon sun and drying wind. Morning sun is fine; in full exposure the fronds bleach and crisp. It suits subtropical, warm temperate and cool temperate gardens, and it is frost hardy once established, though young plants in a frost pocket want an overhead canopy at first.

Soil. Rich and moisture retentive, with plenty of compost or leaf litter. It tolerates wet feet, so a low damp part of the garden is an advantage. Mulch generously and never let the root zone bake.

Water and feed. Water is the whole game. Keep the soil moist, and in dry or windy weather water the trunk as well as the ground, because the fibrous trunk absorbs moisture directly. Liquid feed monthly through the warm months.

Pruning. Cut old brown fronds off close to the trunk once they have finished. Wear gloves and long sleeves: the fine hairs on the fronds and trunk irritate the skin of many people.

What to expect when it arrives

We grow it in a 300mm pot and in packs of six 200mm plants. Both are young ferns with a crown of fronds and little or no visible trunk yet, which is what a tree fern looks like at this stage.

Ferns dislike dry air in transit, so expect some frond edges to look tired on arrival. Cut off anything badly damaged, water thoroughly, and keep the plant in shade while it settles. New fronds usually unfurl within four to eight weeks in warm weather. Plants are delivered Australia wide, with delivery from $29.95. Every plant is covered by our 30 day healthy plant guarantee.

Plant care guides and related reading

• Browse the full range of ferns for shady areas.
• Read our guide to creating the right environment for ferns.
• Find companions in plants for partial shade.

Common questions

How fast will it grow a trunk?

Slowly. Around 20 to 30cm a year with steady moisture and shelter, which puts a 5m specimen at fifteen years or more. Nothing makes a tree fern quick.

Can I grow it in a pot long term?

Yes, in a pot 500mm or wider with good drainage and a rich mix. Potted plants stay smaller and need watering far more often, sometimes daily in summer.

Why do the fronds make my skin itch?

The trunk and frond bases carry fine hairs that irritate skin on contact, which is what gives the rough tree fern its name. Wear gloves and long sleeves when pruning or planting.