Winterising Your Garden: Which Plants Need Fleece, Which Need Mulch and Which Are Fine as They Are
A complete guide to winterising your garden: frost protection, overwintering tender plants, lawn care, winter pruning rules, pond care, and a month-by-month checklist from October to February.
Most plants don’t die from winter cold. They die because their owner didn’t prepare in time — or made small, easily avoided errors: mulching right against a stem, leaving pond water to freeze completely, or cutting the grass too short going into the first hard frost.
The cold itself is rarely the killer. It’s the freeze-thaw cycle — water expanding inside plant cells, cracking tissue from the inside out — that causes the real damage [2]. A well-prepared garden can come through even a harsh UK winter remarkably intact. A neglected one may not, and some of the damage only shows up in spring, when you’re left wondering why a beloved agapanthus has gone soft or why the terracotta pot on the patio cracked clean through.
This guide covers everything: how to protect plants with horticultural fleece and cold frames, how to overwinter tender perennials, the correct lawn care approach for winter, which plants to prune now and which to leave until spring, pond winterisation, tool storage, and a month-by-month checklist from October through to February.
For general advice on keeping your garden healthy through the cold season, see our guide to winter garden care.
What Frost Actually Does to Plants
Water is the common thread behind almost every type of winter plant damage. When temperatures drop below 0°C, the water inside plant cells freezes and expands by around nine percent. That expansion ruptures cell walls, turning firm tissue into mush. The damage is usually invisible while the plant is still frozen — it only becomes apparent as it thaws, when affected tissue collapses and turns black [2].
Two types of frost are worth distinguishing. An air frost occurs when the air temperature drops below 0°C. A ground frost occurs when the soil surface drops below 0°C even though the air above stays marginally warmer — more common on clear, calm nights, and capable of catching plants off guard even when forecasts look mild. If the overnight forecast shows 1–2°C, treat it as a frost risk and act accordingly.
Horticultural Fleece: Single vs Double Layer
Horticultural fleece is the most versatile frost-protection tool in the garden. It works by trapping a layer of warmer air around the plant, raising the local microclimate temperature just enough to prevent ice crystals forming in plant tissue.
Fleece comes in two main weight grades. Lightweight fleece (17 g/m²) gives minimal protection — good for buffering a light frost or extending the growing season in mild conditions — but allows better light transmission and air circulation. Heavy-duty fleece (35 g/m²) offers approximately 2°C of frost protection, according to the RHS [1]. For most purposes, the heavier grade is the better choice for winter protection.
For a severe cold snap — when overnight temperatures are forecast at –3 or –4°C — doubling up pays off. Two layers of fleece can provide 4–5°C of protection. The technique is simple: drape one layer and anchor the base, then add a second over the top. Remove during the day when temperatures climb above 5°C to prevent overheating.
Practical rules for using fleece effectively:
- Tent loosely over plants rather than wrapping tightly against foliage — trapped condensation can freeze directly onto leaves
- Secure the base with tent pegs, stones, or wire clips; wind will undo careful draping within an hour
- On sunny days, even cold ones, check for overheating — fleece creates a modest greenhouse effect
- For a sustainable alternative, the RHS now recommends wool fleece or plant-based BioFleece, which biodegrade rather than fragmenting into microplastics [1]
Cloches and Cold Frames
Cloches and cold frames go a step further than fleece, offering more substantial and permanent protection. According to Missouri University Extension, a well-sited cold frame maintains an interior temperature 5–10°F (roughly 3–6°C) warmer than the outside air [16] — enough to protect most half-hardy plants through a typical UK winter.
Cloches — glass domes or plastic lantern types — work best for individual plants or short rows. Glass provides better light transmission and thermal mass; plastic is lighter, safer and cheaper. Use them to protect individual specimens, cover rows of vulnerable plants, or ripen late-season crops that are still on the plant.
Cold frames allow more control: the lid opens for ventilation, which is critical on brighter days. Interior temperatures can exceed 30°C within an hour if the lid stays closed on a sunny winter day [6]. Open the lid whenever outside temperatures are above 10°C to allow air circulation and prevent Botrytis (grey mould), which thrives in cold, stagnant, humid conditions.
A south-facing cold frame with brick or wooden sides retains daytime warmth well into the night. For extra insulation in the coldest months, line the inside of the lid with bubble wrap. A free DIY version is simply an old glazed window propped at an angle over a low brick or wooden frame.
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Mulching for Frost Protection
A thick layer of organic mulch acts as a thermal blanket for the soil, moderating the freeze-thaw cycles that cause roots to heave and crowns to rot. It’s the most cost-effective protection for borderline-hardy plants — and for many, it makes the difference between lifting tubers every autumn and simply leaving them in the ground.
The RHS recommends a minimum depth of 5–7.5 cm for general mulching, but for frost protection around tender crowns, aim for at least 7.5–10 cm [4][5]. I apply mulch in early November once top growth has been frosted back, working around each plant and keeping a clear collar immediately against the stem — direct contact between mulch and woody stems traps moisture and encourages collar rot [5].
The best mulching materials for frost protection are those that trap air rather than compact: straw, chipped bark, and leaf mould all work well. Avoid fresh green plant material or wet compost — you want a light, dry layer that insulates, not a wet mat that freezes solid around the crown.
Timing matters: don’t apply mulch to ground that’s already frozen, as you’ll lock cold in rather than keep warmth in. Apply in October or early November, before the first hard freeze [4].
Plants that respond well to mulch-only winter protection in most UK gardens include deciduous agapanthus, globe artichokes, ginger lily (Hedychium), and — in mild south-west and coastal regions — cannas. Dahlias can be mulched in situ in the warmest parts of the country, but should be lifted in colder inland areas. For a full guide to materials, depth, and timing for different plant types, see our mulching guide.
Overwintering Tender Plants
Not every plant needs to come indoors, but knowing which ones do — and when — is one of the most consequential winter gardening decisions you’ll make. The RHS hardiness rating system provides a clear framework:
| RHS Rating | Examples | Min. Temp | Recommended Action |
|---|---|---|---|
| H2 (tender) | Pelargoniums, fuchsias, citrus | 1°C | Bring indoors or to a heated greenhouse |
| H3 (half-hardy) | Dahlias, cannas, agapanthus | −5°C | Lift tubers or apply thick mulch in mild regions |
| H4 (mod. hardy) | Rosemary, lavender, hydrangeas, acers | −10°C | Cold frame or sheltered position |
| H5 (hardy) | Hostas, daylilies, most shrub roses | −15°C | In-situ mulch is sufficient |
Move H2 plants — pelargoniums, fuchsias, citrus, tender salvias — indoors before mid-October in most UK regions, and by early October in Scotland or at elevation [4]. The first frost catches many gardeners out; once the foliage blackens, tissue damage is already done and cannot be reversed.
Heated vs unheated greenhouse
An unheated greenhouse is sufficient protection when outside temperatures stay above −5°C, provided it’s well insulated. Lining interior walls and the underside of the roof with bubble wrap can reduce heat loss by 40–50%, according to Greenhouse Stores UK [17] — a significant improvement for minimal cost. Aim for a minimum nighttime temperature of 1–7°C. Open vents a crack on days above 10°C to prevent Botrytis, which thrives in cold, humid, stagnant air.
A heated greenhouse with a thermostat-controlled fan heater set to 2°C is sufficient for most H2 plants. Citrus need a minimum of 5–7°C; tropical species require 10–13°C. Good bubble wrap insulation is the single biggest factor in keeping running costs down.
Lifting dahlias and cannas
Wait until the first frost blackens the foliage, then [4]:
- Cut stems to 5 cm above the base
- Fork tubers out carefully — any cuts or bruises will rot in storage
- Leave inverted in a frost-free shed for two to three weeks to drain
- Pack in trays of dry sand, compost, or vermiculite at around 5°C
- Check monthly through winter; discard any soft or rotting tubers immediately
Protecting Containers and Pots
Cold doesn’t crack terracotta pots — water does. Unglazed clay is porous, absorbing moisture from the compost inside. When that moisture freezes, it expands by around nine percent, forcing the clay apart from within. Repeated freeze-thaw cycles over a single winter will crack even a substantial, well-made pot [22].
The most at-risk pots are small unglazed terracotta pieces, especially those without adequate drainage holes or left sitting in waterlogged saucers. Plastic pots are naturally frost resistant. Glazed ceramics are intermediate — the glaze reduces moisture absorption, but can flake where it traps water in hairline cracks.
Three ways to protect pots over winter:
- Bubble wrap — wrap the pot exterior with two layers, air-bubble side facing the pot, secured with garden twine. This buffers the freeze-thaw cycle without restricting drainage. Do not wrap the foliage.
- Double potting — place the pot inside a larger plastic container and fill the gap with dry straw or bark for added thermal mass.
- Elevation and siting — raise all pots on feet or bricks to prevent waterlogging, move against a south-facing wall, and group containers together. Grouped pots share warmth and reduce exposed surface area [3].
Non-frost-proof ceramics — any pot clearly marked as not frost resistant — should be moved into a shed, porch, or unheated greenhouse for winter.
Lawn Winter Care
The last mow of the year
Maintain your lawn at 30–35 mm through autumn and winter [20]. This is deliberately higher than a summer cutting height — longer grass insulates the root zone and recovers more quickly from frost damage. Never cut lower than this in cold months; scalped grass is far more vulnerable to both frost injury and fungal disease.
Grass stops growing actively below 5°C but may continue putting on slow growth through mild UK winters. Mow in dry, frost-free conditions as needed, and stop immediately if the ground feels hard or the surface is visibly frosted.
Aeration
The best time to aerate your lawn is September or October, while the soil is still workable and warm enough to begin recovering before winter sets in [20]. For compacted or clay-heavy lawns, hollow-tine aeration — which removes plugs of soil rather than just puncturing the surface — makes a more lasting difference than simple spike aeration. After hollow tining, brush horticultural grit into the holes: it stays open over winter and improves drainage and airflow throughout the cold months. Mid-winter aeration is not recommended — frozen or waterlogged ground makes it counterproductive and potentially damaging.
Why you should never walk on frosted grass
Frost freezes the water inside grass cells. Walking on frozen grass ruptures those cell walls, causing permanent brown footprints that only fill in when new growth returns in spring. A single path across a frost-covered lawn can leave visible brown footprints for weeks — I learned this taking a shortcut to the compost bin one January morning [20]. Keep children and pets off frosted lawns, and site any regular winter paths on hard standing rather than across the grass.
Autumn lawn feed
Apply a potassium-rich autumn lawn fertiliser in October. High-potassium feeds harden the grass, improve root development, and build resistance to both frost and disease. Avoid nitrogen-rich feeds after August — they drive soft, leafy growth that’s highly susceptible to frost damage and fungal attack over winter.
Winter Pruning: What to Cut and What to Leave Alone
Winter is the right time to prune a useful list of plants — but cutting the wrong plants in cold, wet weather causes more damage than skipping the job entirely. Here’s the full picture.
Green light: prune October to February
Wisteria — the two-prune system is the key to reliable flowering. The summer prune (August) shortens new growth to five or six leaves. The winter prune (January–February) then cuts those same sideshoots back to just 2–3 buds from the main woody framework, according to Ashridge Nurseries [15]. The winter prune is the critical step: it concentrates the plant’s energy into the flower buds at the base of each sideshoot rather than pushing it into leafy growth. Skipping it consistently results in a lush, impressive plant that flowers poorly.
Roses — the RHS recommends late winter for most roses: mid-February in the south and warmer areas, and March in colder northern gardens [8]. Hybrid tea and floribunda roses should be cut back hard to 15–45 cm. David Austin and repeat-flowering shrub roses are reduced by 30–50%. All cuts should be made no more than 5 mm above an outward-facing bud, angled downward to shed water and minimise die-back [9].
In October, reduce tall rose stems by about one-third to prevent windrock — this is a structural job to stabilise the plant for winter, not the full annual prune.
Also prunable in winter: apple and pear trees (November to mid-March, aiming for an open wine-glass shape), autumn-fruiting raspberries (cut all canes to ground level), Group 3 clematis (cut to 10–15 cm), blackcurrants (remove one quarter of old stems), and gooseberries (sideshoots back to 3 buds from the base).
Red light: do not prune in winter
Stone fruits (cherries, plums, apricots, peaches) — never prune in cold, wet weather. Open wounds in winter are highly susceptible to silver leaf disease (Chondrostereum purpureum), a fungal infection that colonises pruning cuts and progressively kills branches across the whole tree. Prune stone fruits in early to midsummer only, when the risk of infection is lowest [8].
Spring-flowering shrubs (forsythia, magnolia, camellia, lilac) — these flower on the previous year’s growth. Pruning in winter removes the exact shoots that carry next spring’s flower buds. Prune immediately after flowering finishes instead.
Ornamental grasses — leave standing all winter. The old stems protect the crown from frost and provide valuable wildlife habitat and structural interest. Cut down to 10–15 cm in late February, just before new shoots emerge [14].
Frost-tender shrubs (ceanothus, pittosporum, myrtle) — never prune in cold weather; wait until late spring when all frost risk has passed.
Pond Winterisation
Leaf management: start in September
Fit a leaf net over the pond in September or early October, before the main leaf fall begins. Decaying leaves release ammonia and other toxic gases that deplete oxygen — a single autumn’s worth of unnetted leaves can create serious water quality problems by midwinter [18]. Remove the net in February once leaf fall is complete [14].
Adjusting the feeding regime
Switch to a wheat germ-based fish food when water temperature drops below 10°C — it’s considerably easier for fish to digest in cold conditions. Stop feeding entirely once the temperature falls below 4°C [18][19]. At this point fish enter semi-hibernation, their metabolism slows dramatically, and undigested food left in the water simply begins to rot, depleting oxygen as it breaks down. A simple pond thermometer takes all guesswork out of the timing.
Pump removal
Remove pond pumps and fountains before temperatures reach freezing — typically late October or November in most of the UK. Running a pump in deep winter circulates cold surface water down to the warmer layers where fish shelter, directly chilling them at the depth they’re trying to avoid [7][19]. Store the removed pump in a frost-free location, ideally submerged in a bucket of clean water to prevent internal seals drying out.
Ice management: the floating ball method
Float a tennis ball or dedicated pond ball on the water during cold spells. Wind keeps the ball moving, delaying ice formation over a small area and maintaining an opening for gas exchange — toxic gases escape and oxygen enters [7].
If the pond does freeze over completely, melt a hole by placing a pan of hot (not boiling) water on the surface and letting the heat conduct through. Never smash the ice with a hammer or spade — the shockwaves travel through the water and can kill or seriously injure fish [7].
Tool Maintenance and Winter Storage
The quiet months between December and February are ideal for tool maintenance. One afternoon’s work extends the life of good tools by years and makes every gardening task in the year ahead more efficient.
Cleaning
Remove caked mud with a stiff brush and warm water. For rust, make a paste of white vinegar and table salt — the salt boosts the acidity — apply to the affected area, leave for a few hours, then scrub off with a wire brush [21]. Rinse and dry thoroughly before oiling. Remove sap from secateurs and pruning saws by wiping with white spirit on a cloth.
Sharpening
Sharpen spade and hoe edges with a flat whetstone held at the blade’s natural bevel angle. Keep secateurs sharp enough to make clean cuts — blunt blades crush stems rather than cutting them cleanly, which provides an easy entry point for fungal disease at the wound site [21].
Oiling
Oil all metal parts with boiled linseed oil, which penetrates metal and creates a rust-resistant barrier. Apply the same oil to wooden handles to prevent the wood from drying and splitting over years of use [21]. For the pivot points on secateurs and shears, one or two drops of machine oil is all that’s needed.
A useful shed habit: keep a bucket of sand mixed with boiled linseed oil near the door. Plunging clean metal tools into it before hanging them up gives a quick clean-and-oil in a single step.
Service the lawnmower in January — check the oil, inspect the spark plug, set the blade height for spring, and clean the underside of the deck before the first cut of the new year [12].
Month-by-Month Winter Checklist
October
- Apply autumn lawn fertiliser (high potassium); hollow-tine compacted areas and brush grit into the holes [10]
- Reduce tall rose stems by one-third to prevent windrock
- Move tender plants (citrus, fuchsias, pelargoniums) indoors before mid-October
- Leave dahlias and cannas until the first frost blackens the foliage, then lift
- Raise all pots on feet; wrap terracotta in bubble wrap or hessian
- Fit leaf netting over the pond
- Line greenhouse walls and roof with bubble wrap before temperatures drop
- Rake fallen leaves and stack them to make leaf mould (ready in 12–18 months)
- Plant garlic: 15 cm apart, tips 5 cm below the surface
November
- Apply 7.5–10 cm of mulch around the crowns of borderline-hardy plants: agapanthus, gunnera, tree ferns [11]
- Lift dahlia tubers; cut stems to 5 cm, drain inverted for two weeks, then pack in dry compost at 5°C
- Remove pond pump and fountain before temperatures reach freezing; switch fish to wheat germ food and stop feeding once water drops below 10°C
- Begin pruning apple and pear trees; cut autumn-fruiting raspberries to ground level
- Continue mowing at 30–35 mm in mild, frost-free spells; stop if ground is frozen or waterlogged
- Move non-frost-proof ceramics under cover; wrap remaining pots in bubble wrap or hessian
December
- Prune wisteria: cut sideshoots to 2–3 buds from the main woody framework [12]
- Prune climbing roses; cut grapevine side-branches to 1–2 buds from the main rod
- Float a ball on the pond to maintain a gas-exchange opening in the ice
- Clean out the shed; clean, sharpen and oil all tools [12]
- Monitor greenhouse: maintain minimum 1–2°C overnight; reduce watering; remove yellowed leaves to prevent Botrytis
- Service the lawnmower
January
- Continue winter pruning: apple and pear trees, wisteria, hybrid tea roses where needed [13]
- Prune gooseberries (sideshoots to 3 buds); remove one quarter of old blackcurrant stems
- Check stored tubers and bulbs; discard anything soft or showing signs of rot
- Plant bare-root roses, hedging and shrubs when the ground is not frozen
- Service power tools ready for the new season [13]
February
- Prune hybrid tea and floribunda roses: mid-February in the south, wait until March in northern gardens [14]
- Cut down ornamental grasses to 10–15 cm before new shoots emerge [14]
- Firm in any plants that have been loosened by frost heave
- Knock accumulated snow off evergreen shrubs promptly to prevent branch breakage
- Remove pond leaf netting [14]
- Protect peach and nectarine blossom with fleece if late frost is forecast
- Spread compost over beds as the soil begins to warm ahead of spring growth
Frequently Asked Questions
When should I start winterising my garden?
Start in early October. The most time-sensitive tasks — moving tender plants indoors, aerating the lawn, applying autumn lawn feed, fitting pond leaf nets — need to happen before the first hard frost. Waiting until November means several of the most important jobs are already too late.
Can I use regular household bubble wrap to insulate pots?
Yes, and it works well. For durability outdoors, UV-stabilised bubble wrap lasts longer — standard domestic wrap can become brittle and tear within a single season when exposed to winter frost and sunlight. Double-wrap the pot exterior, air-bubble side facing the pot, and secure with garden twine.
Is it okay to walk on my lawn in winter?
In mild, frost-free conditions, light footfall is fine. Never walk on frosted grass — the pressure ruptures frozen cell walls, causing permanent brown footprints that only recover when new spring growth fills them in. Keep children and pets off frosted lawns too, and redirect regular foot traffic onto hard paths.
When should I remove frost protection in spring?
In most UK regions, late March to April is safe for removing fleece and mulch from tender plants. Late frosts in April are not uncommon in northern England and Scotland, so watch the extended forecast rather than going by date alone. Remove greenhouse bubble wrap lining in early April to restore light levels for spring growth.
Do all pots need to come indoors?
Only pots clearly marked as not frost resistant need to come under cover. Most plastic pots, and terracotta pots rated frost resistant, can overwinter outside with bubble wrap and raised feet. Check the label — frost resistance ratings vary between manufacturers and pot styles, and a glazed ornamental pot that looks robust may be more vulnerable than it appears.
Getting Your Garden Through Winter
Winterising your garden isn’t a single task — it’s a sequence of decisions spread across five months, each one protecting what you spent the rest of the year building. Once you know the order — October for tender plants and lawn prep, November for mulching and pond care, December for pruning and tools, January and February for fine-tuning — it stops feeling like a burden and becomes a natural seasonal rhythm.
Start with the October checklist. Work through the pond, the pots, and the tender plants first. Everything else follows logically from there. For ideas on what to keep growing while the garden rests, see our guide to what to plant in winter.
References
- Royal Horticultural Society. “Fleece and Crop Covers.” RHS.
- Royal Horticultural Society. “Frost Damage.” RHS.
- Royal Horticultural Society. “Preventing Winter Damage.” RHS.
- Royal Horticultural Society. “Overwintering Tender Plants: Lifting or Mulching.” RHS.
- Royal Horticultural Society. “Mulches and Mulching.” RHS.
- Royal Horticultural Society. “Coldframes and Mini-Greenhouses.” RHS.
- Royal Horticultural Society. “Pond Care and Maintenance.” RHS.
- Royal Horticultural Society. “Shrub Rose Pruning Guide.” RHS.
- Royal Horticultural Society. “Rose Pruning: General Tips.” RHS.
- BBC Gardeners’ World. “October: What to Do Now.” BBC Gardeners’ World.
- BBC Gardeners’ World. “November: What to Do Now.” BBC Gardeners’ World.
- BBC Gardeners’ World. “December: What to Do Now.” BBC Gardeners’ World.
- BBC Gardeners’ World. “January: What to Do Now.” BBC Gardeners’ World.
- BBC Gardeners’ World. “February: What to Do Now.” BBC Gardeners’ World.
- Ashridge Nurseries. “When to Prune Wisteria in Winter.” Ashridge Trees & Plants Blog.
- University of Missouri Extension. “Hotbeds and Cold Frames.” Extension Publication G6965.
- Greenhouse Stores UK. “Overwintering Plants: A Guide to Protecting Them from UK Frosts.” Greenhouse Stores Blog.
- Pond and Garden Design. “Pond Winterisation Guide.” Pond and Garden Design Blog.
- Pond Liners Online. “Winterising Your Fish Pond and Pump.” Pond Liners Online Blog.
- TruGreen UK. “How to Prepare Your Lawn for Winter.” TruGreen.
- Squire’s Garden Centres. “How to Take Care of Your Garden Tools in Winter.” Squire’s Garden Advice.
- Garden Doctor. “Frost-Proofing Terracotta Pots.” Garden Doctor Blog.
