Cyathea australis - S

About the Cyathea australis - S

Cyathea australis, also known as the Rough Tree Fern, is an evergreen tree fern from eastern and southeastern Australia. The species develops an upright, rough trunk topped by a broad crown of dark green, finely divided fronds. In size S, this tree fern is suitable for container cultivation and makes a striking, architectural foliage plant.

Characteristics

Origin: Cyathea australis is native to eastern and southeastern Australia. There, the species grows in rainforest and open forest, particularly on moist, shaded slopes and in gullies.

Family: Cyatheaceae, the tree fern family.

Position: A sheltered position in partial shade, with filtered light and protection from drying winds. Size S can be placed outdoors during the warmer, frost-free months and should be moved to a bright, frost-free greenhouse or conservatory before winter.

Height: In its natural range, the trunk can reach approximately 2.5 to 20 metres in height and the fronds can grow 2 to 3 metres long. In a container and under cooler growing conditions, the plant remains considerably more compact.

Flowering period: Not applicable. As a fern, Cyathea australis does not produce flowers and reproduces by spores.

Flower colour: Not applicable, because this tree fern does not produce flowers.

Hardiness: The species tolerates cool temperatures above freezing, but not frost. Under Dutch conditions, overwinter size S in a bright, frost-free place, preferably at 10°C or above.

Soil type: A humus-rich, slightly acidic to neutral and well-drained soil that can remain evenly moist without becoming waterlogged.

Care

Light: Provide filtered light or partial shade. Acclimatise the plant gradually to a brighter position and protect size S from sudden, intense midday sun.

Water: Keep the potting mix evenly moist and do not allow the root ball to dry out completely. Allow excess water to drain freely. In hot, dry weather, any established trunk may also be moistened; in winter, avoid allowing water to remain in the crown for extended periods.

Fertiliser: During active growth, feed regularly with a suitable liquid fern fertiliser or a mild organic fertiliser. Follow the recommended dosage and reduce feeding when growth slows.

Pruning: Remove only fully dead or damaged fronds. When pruning, do not damage the trunk or the central growing point.

Repotting: Repot preferably in spring, once the roots have largely filled the available pot space. Choose a slightly larger container with drainage holes and use a humus-rich, airy and well-drained potting mix.

Humidity: High humidity supports healthy frond development. Protect the plant from dry heated air and drying winds, while also ensuring adequate air movement.

Special features: The species develops a characteristic rough trunk with persistent frond bases and reddish-brown scales. The bases of the frond stalks may bear conical spines, so handle the plant with care.