Tree ferns are not actually trees, but with their tall ‘trunks’ and dramatic crown of fronds, they do look very tree-like. The trunk is actually a mat of fibrous aerial roots that need to be kept moist. The most common species tree fern grown in the UK is Dicksonia antarctica. Native to Tasmania, its one of the oldest plants in the world. Its classed as half hardy but will grow in the UK and tolerate quite cold temperatures.
Tree ferns are very slow growing and work particularly well in urban spaces, where they look good against hard surfaces and look particularly striking in shady courtyards. When buying a tree fern, always make sure it has been responsibly sourced.
Tree ferns are truly magnificent plants that can transform any indoor or outdoor space with their prehistoric elegance. With proper care, these gentle giants can thrive for many years. This comprehensive guide provides tips on choosing the right tree fern, planting, watering, fertilizing, and troubleshooting common issues.
Overview of Tree Ferns
Tree ferns are ancient plants that evolved over 200 million years ago alongside dinosaurs, There are around 1000 species found throughout tropical and subtropical regions worldwide, The most popular indoor varieties are the Australian tree fern (Cyathea cooperi) and Tasmanian tree fern (Dicksonia antarctica)
Tree ferns have a trunk covered in fibrous roots that support a crown of lacy fronds. They thrive in warm, humid environments similar to a rainforest understory. With the right growing conditions tree ferns can reach towering heights of 30-50 feet in their native habitats.
Choosing the Best Tree Fern
When selecting a tree fern, choose a variety suited to your climate The Tasmanian tree fern handles cooler temperatures down to 30°F better than the Australian tree fern. For tropical climates, the Australian tree fern grows larger and faster
Inspect the trunk and fronds for signs of pests, disease, or damage. Choose a plant with several unfurled fronds and a healthy root system on the trunk. Locally grown ferns are best acclimated to conditions.
Providing the Ideal Growing Conditions
Light
Tree ferns thrive in bright, indirect light similar to a rainforest understory. When grown indoors, place near an east or west window. Outdoors, choose a shady spot protected from intense midday sun.
Temperature
Keep tree ferns between 60-80°F. Move outdoor container plants indoors if temperatures drop below 50°F. Avoid cold drafts and heating vents for indoor plants.
Soil
Use a rich, acidic, humus-based potting mix. Amend outdoor planting beds with compost, peat moss, pine needles, and sand.
Water
Keep soil consistently moist but not soggy. Water when the top inch becomes dry. Mist the trunk and fronds frequently to increase humidity. Ensure proper drainage.
Humidity
High humidity around 60-80% is vital. Boost indoor humidity with misting, nearby plants, and a humidifier. Shelter outdoor plants from drying winds.
Fertilizer
Feed monthly with balanced organic fertilizer during spring and summer. Dilute any liquid fertilizer by half.
Caring for Tree Ferns Long-Term
Repotting
Repot rootbound ferns in early spring before growth resumes. Choose a pot 2-4 inches larger and refresh some soil.
Pruning
Remove dead or damaged fronds at the base using sterilized pruners. Wipe dust from leaves to improve air circulation.
Pest Control
Check regularly for scale, mealybugs, and mites. Isolate and treat using horticultural oils or insecticidal soaps.
Overwintering
In borderline climates, wrap trunks with horticultural fleece and fill crowns with straw. Move container plants indoors if colder than 30°F.
Troubleshooting Common Tree Fern Problems
Yellowing Fronds
This usually signals too much sun, under-watering, or insufficient humidity. Adjust conditions and prune damaged fronds.
Drooping Fronds
Indicates underwatering or low humidity. Increase watering frequency and misting.
Leaf Drop
Caused by cold drafts, pests, or transplant shock. Improve air circulation and acclimate new plants.
Slow Growth
Results from insufficient light, cool temps, rootbound plants, or underfeeding. Fertilize regularly and repot as needed.
Rotting Trunk
Due to overwatering or crown rot. Allow soil to partially dry before watering again. Avoid wetting the crown.
Final Tips for Tree Fern Success
-
Gradually acclimate new plants to avoid transplant shock.
-
Use rain or distilled water to prevent mineral buildup.
-
Add pebbles below pots for drainage and aeration.
-
Rotate plants periodically for even growth towards light.
-
Monitor closely for pests in humid environments.
With proper care tailored to their preferences, tree ferns can thrive for decades as living fossils in any indoor jungle or tropical garden. Their gracefully arching fronds and prehistoric appeal make tree ferns well worth the minimal care required.
Where to grow tree ferns
Tree ferns can be grown in borders or containers and need a damp, shady, sheltered spot, out of direct sunlight and neutral to acid soil. They grow well in boggy conditions near water too.
Tree fern varieties to try
- Dicksonia antarctica – one of the hardier tree ferns. It works well when combined with other ferns and shade tolerant plants, or in an exotic planting scheme. The Royal Horticultural Society has given it its Award of Garden Merit (AGM).
- Blechnum tabulare – an evergreen fern with large fronds that can reach up to 1m in length, when mature. It’s not a true tree fern, but will eventually develop a trunk.
- Dicksonia fibrosa – an evergreen tree fern that grows to 6m, with dark green, fronds up to 2m long.
- Cyathea australis – these evergreen tree ferns are slightly more tender and may lose their fronds in colder areas.
- Dicksonia youngiae – a hardy fast-growing tree fern with native to the rainforests of Australia.
Five Mistakes to Avoid When Growing Tree Ferns – Dicksonia antarctica
FAQ
How often do you water a fern tree?
Keep the soil moist at all times. Australian tree ferns are not drought-tolerant and need weekly watering. In extremely dry weather conditions, their need for moisture and humidity is extremely important.
Should I cut the fronds off my tree fern?
In the winter the fronds will die down but do not cut them off until the following spring. Fold the fronds in before wrapping up your tree fern for winter.
Do you water tree ferns from the top or bottom?
It’s important to keep the trunk moist, as these aerial roots rely on that moisture to stay healthy. Here’s how I like to do it: Gently water the crown of the fern. Be careful not to drown the crown—just give it a nice, light soak so the plant gets moisture where it needs it most.
Do tree ferns like sun or shade?
Tree ferns thrive in a humid and shaded position. They will not tolerate temperatures below -5°C. Allow room for your tree fern to spread. Fronds on mature specimens may reach 2m (6ft) or more in length.