Seasonal Gardening Guide

Frost Protection Methods: Row Covers, Cloches and When to Act

Know when frost threatens and how to protect plants: fleece and row covers, cloches, cold frames, mulch, watering tricks and moving pots. Includes what to protect first and what to leave alone.

  • By Verdant Editorial
  • Published
  • Updated
  • 4 min read
Frost Protection Methods: Row Covers, Cloches and When to Act

Quick answers

At what temperature do plants need frost protection?
Tender plants can suffer at 2°C (36°F) and are damaged at 0°C (32°F). Hardy plants tolerate frost. Clear, still, cold nights carry the highest risk.
What is the best way to protect plants from frost?
Cover them with horticultural fleece or a row cover on frames, holding it above the foliage. Cloches, cold frames and moving pots against a warm wall or indoors also work well.
When should I put covers on and take them off?
Cover in the late afternoon before temperatures drop, and remove them in the morning once frost has melted so plants get light and air.
Can I use plastic sheets?
Yes, but only held off the leaves with a frame and removed in the morning. Plastic touching foliage conducts cold and can cause damage and condensation.

Key takeaways

  1. Watch the forecast. Clear, calm, cold nights are the danger.
  2. Cover before dusk and uncover after the frost has melted.
  3. Hold covers off the leaves with stakes or hoops.
  4. Moist soil and mulch hold heat. Water well before a frost.
  5. Protect tender and newly planted plants first.
  6. Keep fleece and frames ready, because frosts arrive without much warning.
Table of contents16 sections
  1. How frost harms plants
  2. Know when to act
  3. Which plants to protect first
    1. 1. Horticultural fleece and row covers
    2. 2. Cloches, tunnels and cold frames
    3. 3. Mulch and watering
    4. 4. Move pots
    5. 5. Improvised covers
    6. 6. Protect blossom
  4. Step by step: protecting for a frost night
  5. Frost damage: what to do
  6. Preventing frost problems long-term
  7. Cold and heat in warmer climates
  8. Mistakes that cost the most
  9. What experienced gardeners do differently
  10. Continue with these guides

A single frosty night can undo months of work. Tomato seedlings planted out a week too early, dahlia foliage blackened in autumn, blossom on a peach tree turned brown: all are the result of cold arriving before the garden was ready. The good news is that protection is simple and cheap, and most plants only need help on a handful of nights each year.

This guide explains how frost damages plants, how to read the weather and the best protection methods. It belongs to the Seasonal Gardening pillar and works with Spring, Autumn and Winter guides, and with The Seasonal Planting Calendar.

How frost harms plants

When temperatures drop below freezing, water inside plant cells can freeze and rupture them. Tender leaves turn dark and limp, flowers and fruit drop and shoots die back. Hardy plants cope because their cells have adapted; tender plants, young growth, blossom and seedlings do not.

  • Radiation frost happens on clear, still nights as heat escapes into the sky. It is the commonest type and the easiest to protect against.
  • Advection frost comes with a cold wind and a sharp temperature drop. It is harder to prevent and needs sheltered, insulated protection.
  • Freeze-thaw cycles in late winter can heave shallow-rooted plants out of the soil.

Know when to act

  • Check the forecast for lows of 2°C (36°F) or below, especially on clear, calm nights.
  • Know your dates: average last spring and first autumn frost, then add a buffer of 1–2 weeks for tender crops.
  • Use a min-max thermometer in the garden; frost pockets and open ground are colder than the forecast.
  • Know your microclimate: low spots collect cold air; walls and slopes protect.

Which plants to protect first

Priority Plants
Highest Tomatoes, peppers, courgettes, beans, basil, cucumbers, dahlias, cannas, tender bedding
High Blossom on fruit trees (peach, apricot, plum, pear), newly planted trees and shrubs, young seedlings
Medium Citrus, tender shrubs (hebe, fuchsia, pelargonium), potted tender plants, early potatoes
Low Hardy perennials, brassicas, leeks, spinach, hardy herbs

1. Horticultural fleece and row covers

Lightweight fleece (17–30 gsm) adds 2–4°C of protection. Drape it over plants or hoops, weight the edges with stones and keep it off the foliage. Use double layers for harder frosts. It lets air and water through, so it can stay on for days.

2. Cloches, tunnels and cold frames

Glass or plastic cloches protect individual plants; polytunnel hoops cover rows; cold frames shelter seedlings and hardening-off trays. Vent them on sunny days to prevent overheating.

3. Mulch and watering

A thick mulch protects roots, and moist soil stores more heat than dry. Water well in the morning before a forecast frost, and mulch tender perennials such as dahlias and agapanthus.

4. Move pots

Bring tender potted plants indoors, into a greenhouse or porch, or group them against a warm south-facing wall and wrap them in fleece.

5. Improvised covers

Old sheets, hessian, cardboard boxes and upturned buckets protect plants on a short-notice night. Remove them in the morning, and do not let plastic touch leaves.

6. Protect blossom

Cover small fruit trees and wall-trained fruit with fleece at night during blossom, and remove it by day so pollinators can reach the flowers.

Step by step: protecting for a frost night

  1. Water the soil thoroughly during the day.
  2. Late afternoon: set stakes or hoops over the plants.
  3. Drape fleece or sheet over the frame, reaching the ground on all sides, and weigh down the edges.
  4. Move potted plants against a wall or indoors.
  5. Check at dawn. After frost has thawed, remove covers so plants get light and air.
  6. Do not prune frost-damaged growth straight away; wait until the weather warms because the dead growth protects what is beneath.

Frost damage: what to do

  • Do not panic; many plants recover. Wait for new growth before cutting back damaged shoots.
  • Water plants with lukewarm water if soil is dry, and mulch to keep roots stable.
  • Feed lightly once recovery growth appears.
  • Replace plants that have not recovered after a few weeks.

Preventing frost problems long-term

  • Choose hardy plants and varieties suited to your zone.
  • Delay planting tender crops until after the last frost (see How to Transplant Seedlings).
  • Use sheltered sites against walls and fences; avoid hollows where cold air pools.
  • Choose late-flowering fruit varieties in frost-prone areas.

Cold and heat in warmer climates

In subtropical regions, frost is occasional rather than regular, and one cold night in January can destroy tender crops. Keep fleece handy, plant tomatoes and peppers in a sheltered spot and cover citrus, bananas and young plants when forecasts show lows near 2°C.

Mistakes that cost the most

  • Covering plants too late, after the temperature has already dropped
  • Letting plastic touch the leaves
  • Leaving covers on during sunny days so plants overheat
  • Planting out tender crops too early
  • Cutting back frost-damaged growth immediately

What experienced gardeners do differently

  • Keep a bundle of fleece, pegs and canes near the door for last-minute covers.
  • Use water-filled bottles or buckets inside cloches to store daytime heat.
  • Record the dates and temperatures of damaging frosts; they reveal your garden’s microclimates.

Continue with these guides

Plan the year with the Year-Round Checklist, extend your harvest with Succession Planting and prepare in Planning for Next Year. Back to Seasonal Gardening.

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