Australian tree ferns (Sphaeropteris cooperi and also known as Cyathea cooperi) are members of the family Cyatheaceae. There are three different genera of tree ferns of which two are native to Australia. The Dicksonia has three species and Cyathea has 12 species growing in Australia. Australian tree ferns will grow well outdoors in the tropical regions of the United States in USDA planting zones 9 and 10. Because they are tropical in nature, tree ferns will not tolerate freezing temperatures. Providing you meet the plant's growing requirements, adding an Australian tree fern to the landscape will be an eye catching, tropical beauty.
Select an area in your garden situated in full shade or partial shade in which to grow your tree fern. Australian tree ferns will not grow well if forced to live in sunny conditions.
Choose an area that is large enough for the Australian tree fern to reach its maximum height and width without interfering with other plants or structures. They can reach a height of 30 feet with a spread of 8 to 15 feet.
Grow the Australian tree fern in soil that drains very well and is amended with organic material. Work manure or compost into the planting area to a depth of approximately 1 foot. Loosen the soil around the planting site so the root system will have an easier time spreading out.
Loosen the roots on container grown ferns before placing then into the ground. If the roots have become pot-bound, carefully pull them apart with your hands so they can spread out easier in their planting site.
Water the Australian tree fern regularly to keep the planting site moist, but not flooded. During periods of hot weather and drought, water the fern approximately three times per week. The tree fern will benefit from regular watering.
Remove any weeds, grasses or other unwanted vegetation from the growing site and keep it weed-free at all times. Keep an area of 3 feet in diameter around the trunk clear of weeds. Place mulch around the planting site to help the soil retain moisture and cut down on new weed growth.
Fertilize the Australian tree fern in early spring, summer and fall with a high-quality 10-10-10- granular fertilizer. Spread the fertilizer around the entire drip line and water in well. Do not allow the fertilizer to butt up against the tree fern's trunk or it can become burned. Apply a fresh application of manure or compost on top of the soil in spring. Water the organic material and fertilizer in well after applying.
Prune as necessary to remove any brown or dead fronds.
Things You Will Need
- Pruning shears
- Pests are usually not a problem for outdoor-grown Australian tree ferns.
- Australian tree ferns reproduce by spores, which are located under their leaves.
- Australian tree ferns have become a problem plant in Hawaii, taking over habitats from native plant species.
- Protect the tree fern from potential frosts or freezes by covering the plant with a blanket, or hanging lights off the tree to keep it warm.