Which Garden Plants Need Frost Protection?

When the first frost forecast of autumn arrives, it's easy to panic and rush to protect everything. But spending time and fleece on fully hardy plants is wasted effort. The key is identifying which plants are genuinely vulnerable and prioritising your time and materials on those.

Plants that definitely need protection

Frost-tender annuals and bedding plants are the first priority — pelargoniums, begonias, impatiens, busy Lizzies, and similar tender bedding plants will be killed outright by any frost. Tender perennials used as summer bedding — osteospermum, argyranthemum, Diascia, and similar — are the same. Container-grown tender plants are more vulnerable than the same plants in the ground because the roots in containers are exposed to the full air temperature on all sides, whereas in-ground roots benefit from soil insulation. Dahlia tubers left in the ground unprotected will be killed by a hard frost in most UK regions.

Vegetables that need protection

Among vegetable crops, the most frost-sensitive are outdoor tomatoes, courgettes, cucumbers, French beans, runner beans, basil, sweet peppers, and aubergines. All of these are killed by even a light frost. Early-planted potato shoots are vulnerable before earthing up. Sweetcorn and pumpkins are killed by frost on the vine and must be harvested before cold arrives. Seedlings of any species are more vulnerable than mature plants of the same type.

• Tomatoes, courgettes, beans: killed by any frost.
• Pelargoniums, begonias: killed by first frost.
• Dahlia tubers: mulch or lift before hard frost.
• Tender perennials: bring inside before first frost.

Plants that do not need protection

Most native trees and shrubs, hardy perennials, and traditional cottage garden flowers need no frost protection at all. Roses — even those often described as "delicate" — are extremely frost-hardy. Hardy bulbs like daffodils, tulips, alliums, and snowdrops thrive in cold conditions and need no protection. Kale, Brussels sprouts, winter cabbages, parsnips, leeks, and other winter vegetables are not just frost-tolerant but actively benefit from cold. Covering these with fleece is unnecessary and may actually cause problems by trapping moisture and promoting disease.

Borderline cases

The trickiest plants to judge are the borderline-hardy ones — those that survive in some gardens but not others depending on severity of winter and local conditions. Fig trees, Ceanothus, Agapanthus, tree ferns, Trachycarpus palms, and similar plants are in this category. For these, protect in their first winter after planting (when root establishment makes them more vulnerable), in unusually cold spells, or if you are in a colder region or exposed garden. After several winters without damage, you can reduce protection as confidence builds.