How to Grow Cyathea – Australian Tree Fern

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Cyathea are tropical tree ferns that can grow to 70 feet (20m) tall. They have pole-like fibrous trunks topped by a crown of large, pinnate fronds. Cyathea can be grown outdoors as specimens. Where not hardy they can be grown in a warm greenhouse in containers.

The species Cyathea cooperi is commonly known as the Australian tree fern. It is the fastest-growing Cyathea and can withstand hard frosts. It can grow to 20 feet tall and 12 feet wide. It starts as a spreading clump before growing upwards; it can spread as much as 6 feet wide in a year.

Cyathea is a genus of more than 600 species of evergreen tree ferns, mainly from mountain ranges in tropical and subtropical regions of the Southern Hemisphere.

Get to know Cyathea

  • Plant type: Fern
  • Growing zones and range: Zones 9-12
  • Hardiness: Hardy to Zone 10
  • Height and width: 3 to 50 feet or more and 3 to 15 feet wide depending on the variety
  • Foliage: Broad, bright green, finely cut fronds
  • Uses: Specimen plant, container plant
  • Common name: Australian tree fern
  • Botanical name: Cyathea
  • Family name: Cyatheaceae
  • Origin: Tropical and subtropical Southern Hemisphere
Australian tree fern, Cyathea australis

Where to plant Cyathea

  • Light outdoors: Grow Cyathea in dappled or partial shade.
  • Soil outdoors: Plant Cyathea in humus-rich, moist soil.
  • Light indoors: Provide Cyathea with bright filtered light and moderate to high humidity.
  • Soil indoors: Use a potting mix of 1 part each of loan, sharp sand, and charcoal, and 3 parts coarse leaf mold or peat.

When to plant Cyathea

  • Set container-grown Cyathea outdoors in spring. Cyathea growing indoors in a greenhouse can be place outdoors in shade during the summer.

Planting and spacing Cyathea

  • Space Cyathea 3 to 15 feet apart depending on the variety.

How to water and feed Cyathea

  • Water Cyathea freely; hose down the trunk on hot, dry days. Water sparingly in winter.
  • Fertilize Cyathea with a balanced liquid fertilizer monthly.

Cyathea care

  • Keep Cyathea out of drying winds.
  • The browning hairs on the fronds can irriate skin, wear long sleeves, hat and neckcloth when working with Cyathea.

Cyathea pests and diseases

  • Rhisoctonia may be a problem on young plants.

Cyathea propagation

  • Sow spores at about 60°F as soon as ripe.

Cyathea varieties to grow

  • Cyathea australis (syn, Alsophila australis). Grows 3 to 10 feet tall and 10 to 15 feet wide; dark green froms to 12 feet long with lance shaped fronds.
  • C. cooperi, Australian tree fern. Fast growing from 6 to 15 feet tall and 10 feet wide; mid-green fronds to 12 feet long.
  • C. dealbata, silver tree fern. Grows to 30 feet tall and to10 feet wide; narrowly ovate, mid to deep green fronts to 10 feet long.
  • C. howeana. Tree fern with slender trunk grows to 6 feet tall and twice as wide; light green scaly fronds.
  • C. medullaris, black tree fern, Sago fern. Wide-spreading tree fern with black stem; grows 30 to 50 feet tall with fronds to 20 feet long; deep green fronds are pale beneath.
  • C. smithii. Upright tree fern gows to 25 feet tall and half as wide; fronds are bright green above and pale beneath.

Written by Stephen Albert

Stephen Albert is a horticulturist, master gardener, and certified nurseryman who has taught at the University of California for more than 25 years. He holds graduate degrees from the University of California and the University of Iowa. His books include Vegetable Garden Grower’s Guide, Vegetable Garden Almanac & Planner, Tomato Grower’s Answer Book, and Kitchen Garden Grower’s Guide. His Vegetable Garden Grower’s Masterclass is available online. has more than 10 million visitors each year.

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