Guide to Growing Dicksonia antarctica

General Information

The botanical name Dicksonia antarctica derives from:

Dicksonia - named in honour of James Dickson, 1738-1822, a British nurseryman.

antarctica - 'southern', or from the Antarctic regions.

Common names for the species include Hardy Tree Fern, Soft Tree Fern, Australian Tree Fern, and Tasmanian Tree Fern.

D. antarctica is endemic to Australia, growing from South-Eastern Queensland, through the NSW and Victoria coastal areas and in Tasmania. In the wild this species prefers to live in moist areas with high water content in wet forests, along creek beds, in gullies and occasionally at high altitudes in cloud forests.

In its native habitat D. antarctica experiences temperatures as low as -13˚C (8˚F). For this reason some growers feel that D. antarctica is fully hardy in Britain. However do not be lulled into a false sense of security. Only Mature plants (4ft+) can be left completely unprotected and these may still lose their fronds although they should re-grow healthily in spring. (See over wintering)

D. antarctica is an attractive fern whose trunk can grow up to 6m x 75cm (20ft x 30in) in height; it has large dark green roughly textured fronds growing to 1.2 – 2.5m in a spreading canopy of up to 6m (20ft) in diameter. D. antarctica is a very slow growing specimen, in cultivation the trunk rarely reaches the maximum figure given. The trunk itself is made up of a central core of very hard woody vascular tissue. This is surrounded by old leaf bases through which root fibers grow.

Planting

The condition in which D. antarctica thrives is in filtered sunlight, loose well drained soils with lots of organic matter and plenty of water. However, this species can still withstand some drying out and can survive in drier conditions. The older the plant the more tolerant it will be to drought. An exposed site will dry plants out more quickly so semi-shade is preferable. Plants in full sun or watered less frequently often result in the development of shorter fronds.

Before planting the trunk, it is recommended that it should be soaked in water for a few minutes. Dig a hole slightly larger than the diameter of the trunk and infill with organic mulch. Plant the log in such a way that as little trunk as possible is buried, while ensuring that it is stable and will not easily topple over easily. Once the trunk is firmly in place, water the trunk copiously.

If preferred D. antarctica can be grown as a pot specimen. Again, plant as shallow as possible, but remember when picking up the pot that the log will fall out if not held upright. After about 1 year, roots should appear from the bottom of the pot. The plant can then be re-potted into a larger container.

Maintenance

The most important maintenance of your D. antarctica is regular watering. At sizes less than 1ft this should be several times a week and daily for the first summer to establish a good root system. Do not spray directly in the ferns crown (top) as in colder weather this may encourage rot. Instead soak the whole trunk, angling the hose from below, the wetter the better.

For plants in containers feeding is necessary after the first year, a small dose of a general purpose fertilizer such a growmore, or fish blood and bone will be adequate. This is less important for plants growing in the ground.

For aesthetic reasons it may be necessary to remove old fronds in the spring, this does not necessarily benefit the plant which subsequently becomes more exposed and susceptible to drying out.

Over wintering

There are three main strategies for providing winter protection to tree ferns: keeping them in a conservatory all year round; overwintering small plants in a protected environment; and protecting larger plants outdoors in situ.

Overwintering smaller plants carefully is important as they are more prone to die if frosts are heavy. Where possible it is advisable where possible to bring any plants 2ft or less into a cool conservatory, greenhouse, or even a shed, where temperatures will be higher. It is also desirable to cover the plant with fleece on those nights with hard frosts for added protection, but remember to water the trunks once or twice a week.

Larger plants, although more hardy, still need some protection. The easiest way to provide this is to is to compact a good amount of straw in the crowns of the ferns to stop ice from freezing the crown. In plants less than 4ft added protection may be necessary by insulating the trunk with polystyrene plants trays belted around the trunk.

Botanical Information and Overview

Family Name: Cyatheaceae.

Genus: Dicksonia.

Species: antarctica.

Position: Partial to full shade.

Soil: Humus-rich, neutral to acid soil.

Growth Rate: Slow.

Eventual spread: 6m.

Max Height: 10m (6m Cultivated).

Hardiness: Half Hardy - they are hardy down to -10˚C and the foliage is hardy to -2˚C.

Winter tips: Protect crown from frost by insulating with straw bound chicken wire.

Summer tips: Keep plants moist, water daily during the hotter periods.

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