Dicksonia are dramatic tree ferns with stout, erect, woody trunks from 8 to 28 inches or more across. With crowns of broad fronds, Dicksonia can be mistaken for palm trees. They can grow to 20 feet tall.
The trunks are actually frond stalks growing together in tight spirals; the stalks are covered with bristly hairs and matted aerial roots The fronds are large; the blade is bipinnate or tripinnate and stiff.
Dicksonia are slow-growing. They can take decades to reach maturity. Young plants 2 to 4 feet tall can be grown in pots for several years without outgrowing the pot.
Dicksonia is best grown where there are few touches of frost each year and where rainfall and humidity is high. They must be protected from drying winds.
Dicksonia is a genus of 25 species that occur mostly in the temperate South Pacific; a few are found in South America.
Get to Know Dicksonia
- Plant type: Fern
- Growing zones and range: Zones 9-12
- Hardiness: Hardy to Zone 9
- Height and width: 10 to 20 feet (3-6m) tall and wide
- Foliage: Large fronds ares stiff with sori located along the margin of the blade
- Uses: Specimen plant, container plant
- Common name: Tasmanian tree fern, wooly tree fern
- Botanical name: Dicksonia
- Family name: Dicksoniaceae
- Origin: Southeast Asia, Australasia, South America
Where to Plant Dicksonia
- Outdoors Dicksonia grows best in partial shade; it can tolerate full sun if the soil is kept moist.
- Outdoors grow Dicksonia in humus-rich, moist soil.
- Dicksonia must be protected from drying wind.
- Indoors, grow Dicksonia in a mix of 1 part each loam and coarse bark, 2 parts sharp sand, and 3 parts leaf mold.
- Dicksonia can be grown in a greenhouse in bright filtered light and moderate humidity; if possible move the plants outdoors in summer.
When to Plant Dicksonia
- Set Dicksonia in the garden in spring.
- Repot Dicksonia only when root bound.
Planting and Spacing Dicksonia
- Space Dicksonia 10 to 20 feet (3-6m) apart.
How to Water and Feed Dicksonia
- Water Dicksonia freely. Dicksonia must have consistent soil moisture
- Fertilize Dicksonia with a high-nitrogen liquid fertilizer monthly.
- Top-dress or pot on Dicksonia in spring.
- Hose the rhizomes daily in hot, dry weather.
- Take care not to damage the growing tips; damaged plants will fail to generate new growth and will eventually die.
Dicksonia Pests and Diseases
- Dicksonia is rarely bothered by pests or diseases.
- Sow spores at about 60°F (16°C) when spores are ripe.
Dicksonia Varieties to Grow
- Dicksonia antarctica, Tasmanian tree fern. Tree-like fern, evergreen in mild climates; massive trunk to 24 inches across covered with thick mat of roots; grows to 20 feet tall and 12 feet wide.
- D. fibrosa. Upright to horizontally arching fern with reddish brown fronds; old fronds form a skirt on the trunk; grows 10 to 20 feet tall.
- D. squarrosa. Tree-like, upright fern with arching fronds; fronds are slivery green above to glaucos underneath; slender black trunk; grows 10 to 20 feet tall .