Protecting Tender Plants with Horticultural Fleece

Illustration of flower bulbs, pots and fleece on an autumn potting bench

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Protecting tender plants with horticultural fleece involves using a soft, fibrous, translucent material to insulate plants against frost, wind, and hail. While fleece is not a substitute for moving highly sensitive plants indoors, it provides a critical buffer against temperature drops. Heavier fleece may provide a small amount of frost protection, often described as around 2°C, but the result varies with wind, moisture, fitting and cold duration. Do not subtract a fixed number from the forecast and assume a tender plant is safe.

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Understanding fleece grades and materials

Not all fleece is the same; the weight of the material determines the balance between insulation and light penetration. Choosing the correct grade is essential for the specific goal of the gardener.

Lightweight fleece (e.g., 17g per sq m): This grade allows for better light penetration and is typically used to advance the growth of young seedlings or protect against light wind. It offers the least amount of thermal protection.
Heavy-duty fleece (e.g., 35g per sq m): This thicker material is better suited for protecting tender plants from frost due to its superior insulation properties.
Polypropylene fleece: A common non-woven plastic-based material. While effective, it is less durable and can be damaged by animals such as foxes.
Plastic-free options: Sustainable alternatives include fleece made from plant-based materials or sheep’s wool. Wool is generally heavier than polypropylene but serves the same insulating purpose.

Using fleece for winter wrapping

When tender plants cannot be lifted or moved to a greenhouse, wrapping is the primary method of protection. This should be initiated at the first warning of frost, typically between September and November.

Wrapping shrubs and climbers

For tender climbers, lower stems can be packed with straw or bracken. This insulation is held in place by wrapping re-used fleece or hessian around canes and securing it with garden twine. For shrubs, smaller specimens can be protected by building a bamboo cane wigwam, packing the interior with straw, and covering the exterior with netting or fleece.

For shrubs growing against walls, a batten can be fixed above the plant to suspend fleece like a drape. This allows the gardener to roll up the covering during mild weather to prevent sweating and rot.

Protecting tree ferns and bananas

Tree fern protection depends on species and local cold. Use species-specific advice for crown and trunk protection; fleece may form part of that wrapping. The trunk is wrapped directly, while fronds are tied upright with straw packing at the centre. Bananas (such as Musa basjoo) are often protected by building a chicken wire cage around the stumps after cutting back frosted leaves. This cage is packed with straw and covered with fleece to block wind, often topped with a waterproof hood to keep rain out of the crown.

Fleece for hardening off tender plants

Fleece is a useful optional tool when transitioning plants from a greenhouse or indoor setting to the outdoors. This process, known as hardening off, typically takes two to three weeks.

If specialist facilities like cold frames are unavailable, plants can be placed in a sheltered, south-facing position and covered with two layers of fleece. This can ease the transition, but start in sheltered light shade and increase exposure gradually; fleece does not guarantee protection from strong sun or cold nights. The process follows a gradual reduction in protection:

Week one: Leave plants outside during the day under two layers of fleece; bring them indoors at night.
Week two: Reduce the covering to one layer of fleece. Towards the end of the week, remove the fleece during the day.
Week three: If weather permits, leave plants outside at night while covered, eventually removing the fleece entirely before final planting.

Do not rely on a fixed temperature gain

Crop covers can retain some warmth and extend the growing season, but a typical gain is not a guaranteed thermostat setting or a promise of harvesting two weeks earlier. Monitor conditions beneath covers, ventilate in mild weather and delay planting tender crops while damaging frost remains possible.

Managing risks and limitations

While horticultural fleece is versatile, it has specific limitations that gardeners must manage to avoid damaging their plants.

Moisture and rot

One of the primary risks of wrapping is the trapping of water. If moisture accumulates under the fleece, it can lead to rot in the crown of the plant. To mitigate this, remove all damp debris from the base of the plant before wrapping and ensure the crown is packed with dry materials like straw. For species that need a rain-shedding roof, use the plant-specific wrapping method and maintain ventilation. Do not seal the whole plant in unventilated polythene, which can trap moisture and overheat in sun.

Pollination and ventilation

Fleece should not be left over insect-pollinated crops, such as courgettes or strawberries, during their flowering period, as it blocks the access of pollinators. Additionally, during extended periods of very mild winter weather, protective covers should be removed temporarily to prevent the plant from “sweating,” then replaced when cold weather returns.

Environmental impact

Polypropylene fleece has a short lifespan and is not currently recyclable through most local council services. To improve sustainability, gardeners are encouraged to re-use old fleece or invest in biodegradable, plant-based, or wool alternatives.

Useful products for this job

The links below open Amazon UK product searches. Check the exact item, seller, current price and compatibility before buying.

Heavy-duty horticultural fleece (35g per sq m): A heavier fleece option for limited frost protection; performance depends on the whole covering and conditions. Compare the maker’s intended use, weight, light transmission and fixing instructions. No single35g/m²threshold guarantees survival. Search Amazon for Heavy-duty horticultural fleece (35g per sq m).
Biodegradable plant-based fleece: An alternative covering material where its durability and plant-protection properties suit the task. Check if the material is fully compostable or requires specific industrial conditions to break down. Search Amazon for Biodegradable plant-based fleece.
Garden twine: Used to secure fleece and hessian around canes when wrapping climbers and shrubs. Ensure it is treated for outdoor use to prevent premature rotting during winter wet. Search Amazon for Garden twine.

Related garden guides

Sources and further guidance

Guidance researched in September 2026. The feature image is an AI-generated illustration. Product guidance is based on published information, not hands-on testing.