How to Grow and Care for Australian Tree Fern
Successfully grow an Australian Tree Fern by mastering its environmental needs. Learn to provide the right balance for this lush plant, indoors or out.
The Australian Tree Fern, Sphaeropteris cooperi, is a striking plant from the subtropical climates of eastern Australia. It is known for its tall, slender trunk, which has a brown, hairy appearance and can reach heights of 15 to 30 feet. This fibrous trunk is topped by a canopy of large, feathery fronds with a delicate, lacy appearance, creating a lush, prehistoric feel. New fronds, called fiddleheads, emerge curled up and covered in silky hairs.
Australian Tree Fern Care Guide
Light
The Australian Tree Fern thrives in bright, indirect sunlight or partial shade. Direct, intense sunlight should be avoided as it can scorch the delicate fronds, causing them to burn and discolor. For optimal growth, position it where it can receive filtered morning sun and be protected from the harsh afternoon sun.
Water
Consistent moisture is necessary for the Australian Tree Fern, which is not tolerant of drought. The soil should be kept evenly moist but never waterlogged. It is beneficial to water the fibrous trunk, as it absorbs and retains moisture for the plant, but avoid watering the crown directly, which can cause rot. Weekly watering is necessary, with increased frequency during especially dry conditions.
Soil
The ideal soil for an Australian Tree Fern is rich in humus and drains well. A peat-based potting mix is a good foundation, and amending it with materials like perlite or orchid bark will improve both aeration and drainage. The plant prefers a soil pH that is slightly acidic to neutral.
Temperature and Humidity
Australian Tree Ferns flourish in warm and humid environments, preferring a consistent temperature range between 65 and 80 degrees Fahrenheit. These ferns are sensitive to rapid changes in temperature or humidity, which can cause the fronds to turn brown. To maintain high humidity levels, you can mist it regularly, place its container on a tray filled with pebbles and water, or use a humidifier nearby.
Fertilizer
During the active growing season of spring and summer, the Australian Tree Fern benefits from regular feeding with a balanced, liquid 10-10-10 fertilizer. This fertilizer should be diluted to half-strength and applied every 4-6 weeks. In fall and winter, cease fertilizing as the plant enters a dormant period.
Growing Indoors vs. Outdoors
When grown indoors, place the fern in a location that provides bright, indirect light to avoid scorching the fronds. A large container is necessary to accommodate its potential size. Maintaining high humidity indoors is also important, often requiring supplemental efforts like misting or using a humidifier.
For outdoor cultivation, this fern is best suited for USDA hardiness zones 8 through 11. Plant it in a location that offers dappled sunlight, mimicking its native habitat, and protection from strong winds, as the large fronds can be easily damaged. In areas on the borderline of its hardiness zones, providing winter protection may be necessary.
Pruning and Repotting
Maintenance for an Australian Tree Fern involves pruning to remove old or dead fronds, which helps maintain the plant’s appearance and health. Use clean, sharp shears to cut away any brown or yellowing fronds at their base. Never cut the top or crown of the fern, as this is the single point for new growth, and cutting it will kill the plant.
Repotting should be done every two to three years or when the fern’s roots have filled its current container. Select a new pot that is only two to three inches wider in diameter than the old one. This prevents the soil from staying wet for too long, which can harm the roots. Handle the root ball carefully to minimize stress on the plant.
Common Problems
Browning frond tips are a result of low humidity or allowing the soil to dry out too much between waterings. Yellowing fronds often point towards overwatering and soil that does not drain sufficiently.
Mealybugs and scale are the most common pests. You can remove them by wiping them off with a cotton swab that has been dipped in rubbing alcohol or by applying an insecticidal soap according to the product’s directions.