Frost protection for plants: getting them safely through winter

Frost: the silent plant killer

It starts innocently enough. A clear night, a quiet morning, a thin layer of ice on the water butt. But for some plants, a night frost of minus five is enough to damage roots, kill buds or cause entire branches to die back. Last year I lost two beautiful hydrangeas because I thought they'd be fine. Not making that mistake again.

GardenWorld helps you visualise your garden's potential after seasonal care. You can see exactly which plants sit where and which ones need extra protection.

Which plants are vulnerable?

Anything from a warmer climate needs watching. Olive trees, citrus trees, palms and banana plants won't survive a British winter without help. But even many garden plants we consider hardy can suffer damage. Young hydrangeas, lavender and rosemary are more vulnerable than you'd think, especially in pots.

The UK's hardiness zone sits around 8 to 9. Check your plant's label: if it lists a lower zone, it needs protection.

Container plants: extra risk

Plants in pots are far more vulnerable than plants in the ground. The pot cools from every side and roots freeze quickly. A plant that sails through winter in the border can perish in a pot.

Method 1: Horticultural fleece and hessian

The workhorse of frost protection. Wrap vulnerable shrubs and trees in fleece or hessian as soon as frost is forecast. Fleece lets light and moisture through whilst keeping temperatures a few degrees higher. Garden centres stock rolls in various sizes.

Never use plastic. It traps moisture and causes mould. On sunny winter days, temperatures under plastic can rise too much, causing the plant to break dormancy prematurely.

Frost jackets and fleece caps

For smaller plants and pots, frost jackets are convenient. Pull them over the plant and tie at the base. They're reusable and easy to store. A few pounds' investment that pays for itself over years.

Method 2: Mulching

A thick layer of mulch around the base of your plants protects the roots. Use leaves, straw, compost or bark chips. Five to ten centimetres will do. The mulch acts as an insulating blanket that dampens extreme temperature swings.

Make sure the mulch doesn't sit directly against the stem. That can cause stem rot. Leave a few centimetres of clearance around the trunk.

Method 3: Sheltered spots

Move vulnerable container plants to a sheltered position. Against a south-facing wall is ideal: the wall stores warmth during the day and releases it at night. Group pots together: they protect each other from the cold.

Stand them on a piece of polystyrene or wooden boards. This insulates the pot from the cold ground. Wrap the pots in bubble wrap or fleece for extra protection.

Method 4: Straw and branches

A traditional but effective method. Cover vulnerable plants with a layer of straw, held in place with branches or chicken wire. Standard roses and climbing roses can be wrapped in straw and tied with twine.

Conifer branches also work beautifully. They shield against frost and wind, allow air circulation and look rather lovely in the winter garden too.

When to protect and when to remove?

Start protecting when frost is forecast, usually from November. Remove protection only once frosts have passed, typically in March or April. Do this gradually: remove covers during the day and replace them at night. This acclimatises the plant slowly to outdoor temperatures.

Watch out for late frosts in April. After a few warm days in March it's tempting to strip everything away, but an unexpected night frost can still cause serious damage.

Prevention beats cure

The best frost protection starts with plant selection. Choose plants suited to your climate zone. That saves you the annual fuss with fleece and straw. But for those few treasured plants you keep despite their tenderness: protect them well and enjoy them year after year.

Want to see how your garden looks in spring when everything has come through winter safely? Discover it on GardenWorld and plan your dream garden.