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
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.
- 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.
- 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.