Tree ferns, such as the popular Dicksonia antarctica, are prized for their exotic beauty and structural presence, making them a focal point in many UK gardens. However, as native plants of the cool, moist forests of Australia and New Zealand, they require winter protection in the UK’s unpredictable and often frosty climate. With a few simple steps, you can ensure your tree fern thrives for years to come.
Why Protect Tree Ferns?
Tree ferns are relatively hardy for their tropical appearance, tolerating temperatures down to -5°C (23°F) for short periods. However, prolonged frosts or temperatures below -8°C (17°F) can damage their delicate crowns and kill the plant. Winter protection focuses on shielding the crown—the growing point at the top of the trunk—and the trunk itself, which stores vital moisture and nutrients.
Step-by-Step Guide to Protecting Tree Ferns
1. Assessing the Conditions
- Know Your Microclimate: Sheltered gardens, especially in milder regions, may require less protection than exposed areas prone to strong winds and frost.
- Monitor Temperatures: Keep an eye on weather forecasts, particularly during cold snaps.
2. Mulching the Base
- Apply a thick layer of organic mulch (e.g., straw, leaf mould, or bark) around the base of the trunk to insulate the roots and soil. This also helps retain moisture during dry winter spells.
3. Wrapping the Trunk
- Use layers of horticultural fleece or hessian to insulate the trunk. Do not use bubble wrap as this doesn’t ‘breathe’ and encourages rot. Avoid excessive tightness to prevent rot.
- For particularly large specimens, you can stuff the wrapping with dry straw for extra insulation.
- Concentrate on the top 40cm of the trunk for large specimens
4. Protecting the Crown
- The crown is the most vulnerable part of the tree fern. To protect it:
- Fill the crown with loose, dry straw or bracken. Horticultural fleece is very good because it’s clean and can easily be removed to shake off snow.
- Cover the filled crown with a layer of fleece or an inverted plastic pot to shield it from rain and frost. Ensure the pot is secured and ventilated to prevent condensation and mould.
5. Provide Wind Protection
- Strong, drying winds can exacerbate cold damage. Position a windbreak (such as a screen, fence, or dense evergreen planting) around your tree ferns, especially in exposed gardens.
6. Watering During Winter
- While tree ferns dislike overly wet conditions in winter, their trunks should not dry out completely. During mild spells, lightly water the trunk and crown if it feels dry. Avoid watering during freezing weather to prevent ice damage.
7. For Potted Tree Ferns
- Move potted tree ferns to a sheltered location, such as a greenhouse, conservatory, or a protected corner of the garden. If this isn’t possible, wrap the pot with insulation, such as bubble wrap, to protect the roots from freezing.
When to Remove Protection
As spring arrives and frosts subside, gradually remove the protective layers to allow light and air to reach the crown. Be cautious, as late frosts in April or May can still damage emerging fronds (known as croziers). Keep some fleece handy for sudden cold snaps.
Final Tips
- Inspect Regularly: Check your tree ferns throughout winter to ensure the protection remains intact and dry.
- Feed in Spring: Once the fronds begin to unfurl, feed with a balanced fertilizer or specialist tree fern feed to encourage vigorous growth.
With proper care, your tree fern will reward you with lush, arching fronds, bringing a touch of the tropics to your UK garden year after year.
