Protecting vegetables from frost
Frost is the gardener's clock — it ends the summer crops and shapes the winter ones — but it needn't be the enemy. A surprising amount comes down to two things: knowing which crops actually need protecting (many don't), and having the right bit of cover to hand for the ones that do. Get those right and a frosty forecast stops being a worry.
The first thing to know is when frost is likely where you are — check your local frost dates so nothing catches you out, in autumn or in spring.
First, know what actually needs covering
Half the battle is realising how much takes frost in its stride. Don't waste fleece on crops that don't want it — save it for the ones that do.
Hardy — leave them be
Take frost happily, some even sweeter for it:
Kale, leeks, parsnips, Brussels sprouts, winter cabbage, swede, garlic, autumn-sown broad beans, and hardy salad like lamb's lettuce and claytonia.
Tender — frost kills them
Harvest or protect before the first frost:
Tomatoes, courgettes, squash, pumpkins, French & runner beans, sweetcorn, potatoes (the foliage), cucumbers and all the tender herbs like basil.
In between sit the half-hardy crops — the ones a sharp frost will damage but a little cover carries through. Those are what the fleece and cloches are really for.
Choosing your protection
There's a ladder of protection, from a sheet you throw over at dusk to a whole growing space. Most plots end up with a couple of these:
- Horticultural fleece
The cheapest, most flexible frost insurance there is. Drape it over a bed or over hoops before a frosty night and it traps a couple of degrees of the soil's warmth — often all a hardy crop needs. Double it up for harder frosts. Keep a roll in the shed to throw over at short notice. On Amazon →
- Cloches & mini-tunnels
Rigid or hooped covers that sit over a row, keeping warmth in and rain off. Better than fleece for carrying salad and seedlings through a sustained cold spell, and they double up to warm the soil for early spring sowings. On Amazon →
- A cold frame
The snug box for the tenderest winter pickings and the best tool for hardening off in spring. A proper upgrade that earns its keep all year. See our cold frames & greenhouses guide.
- A polytunnel or greenhouse
The biggest leap — a whole sheltered space that keeps you cropping right through winter and gets you sowing weeks earlier in spring. See our polytunnels guide.
Using cover well
- Cover before the cold, not during it— the point is to trap the day's warmth, so get the fleece on in the late afternoon, not once the frost has already settled.
- Tuck the edges down— warm air escapes from open sides. Weigh or peg fleece and cloches down all round so they actually hold the heat.
- Give air on mild days— covered crops can cook and grow damp and mouldy in warm or still spells. Vent cloches and frames, and don't leave fleece on through a mild week.
- Don't forget spring— the late frosts of April and May catch out tender plants put out too early. The same fleece protects newly planted-out crops then. Watch your local last-frost date before planting tender things out.
Common questions
How do I protect my vegetables from frost?
Match the cover to the crop: fleece over hardy plants for a few extra degrees on frosty nights, a cloche for salad and seedlings, a cold frame for tender things, a polytunnel to extend the whole season. Know your frost dates, watch the forecast, and keep fleece ready to throw over.
What is the difference between fleece and a cloche?
Fleece is a light fabric you drape straight over plants — cheap, flexible, quick to throw over a whole bed before a frost. A cloche is a rigid cover over a row, giving more warmth and rain protection and lasting longer. Fleece for occasional frosts, a cloche for a sustained cold spell.
Which vegetables survive frost?
Plenty: kale, leeks, parsnips, Brussels sprouts, winter cabbage, swede, garlic, autumn-sown broad beans and hardy salad all take frost in their stride — some taste better for it. Tender crops like tomatoes, courgettes, beans, squash and potatoes are killed by the first frost.
Does fleece really protect plants from frost?
Yes — a single layer typically lifts the temperature beneath by a couple of degrees (more if doubled), often enough to carry a hardy crop through a frosty night. It traps warmth rising from the soil, so hold it off the foliage and tuck the edges down.