For lining a greenhouse through winter, start with UV-stabilised horticultural bubble insulation. It is a practical choice when you want a transparent lining you can take down and reuse. If you only have a few tender plants, a smaller protected area may be more useful than wrapping every pane.
Gardening Naturally’s greenhouse bubble insulation is sold by the metre as well as by the roll, which helps with awkward sizes. A fleece insulation kit offers another route for an aluminium greenhouse. Choose around the plants you are keeping, the light they need and the frame you will attach it to.
Insulation slows heat loss. In a long cold spell an unheated greenhouse can still freeze, so tender plants may need suitable heating or a warmer place to spend the winter.
Which insulation suits your greenhouse?
| Your job | Useful starting choice |
|---|---|
| Line a greenhouse to your own measurements | Horticultural bubble film by the metre |
| Buy fleece and fixings together for an aluminium frame | Greenhouse fleece insulation kit |
| Add removable cover over a small group of plants | Horticultural fleece, supported clear of delicate growth |
Bubble film and fleece both reduce the light reaching plants. For leafy crops you want to keep growing, avoid adding layers simply because there is room for them. For plants resting through winter, reducing heat loss may take priority.
If you prefer Amazon, compare horticultural greenhouse insulation. Check the roll width, length and UV treatment: a large-looking roll of packaging wrap can be a very different purchase.
Best for a reusable lining: horticultural bubble film
Gardening Naturally’s film has 20mm bubbles, three layers and UV stabilisation. It comes in 1.5m and 2.4m widths, with cut lengths and full rolls. The useful choice is the width that covers your bays with manageable joins and little waste.
For a small greenhouse, buying a measured length avoids storing most of a large roll. A wider sheet can reduce joins across a large wall, but it is also more awkward to support while fitting. Sketch the pieces first, especially around the door and roof vents.
Ordinary packaging wrap may be useful for a temporary job if you already have it. For a lining you intend to reinstall, choose material made for prolonged exposure in a greenhouse. Check old sheets for brittleness and damaged air pockets before putting them back up.
Choose greenhouse bubble-film width and length at Gardening Naturally.
Best for buying fleece and clips together: an insulation kit
The Gardening Naturally kit combines 30g fleece with greenhouse clips, including corner fixings. Its size options are based on the greenhouse footprint, from 6ft × 4ft upwards. This is convenient when you want the lining and fixings in one order.
Check the greenhouse shape as well as the nominal size. A tall-sided structure or an unusual roof can need more material than another greenhouse with the same floor area. The supplied clips suit aluminium frames; a timber greenhouse needs fixings appropriate to its construction.
Fleece is also easy to lift away from a small group of plants when the weather improves. If your main aim is occasional overnight cover, buying a smaller amount of fleece may make more sense than a kit for the whole structure. Support it above delicate foliage so it is easy to remove without snagging stems.
Measure the lining, not just the floor
A greenhouse sold as 6ft × 8ft describes its footprint. You still have two side walls, two ends and a roof to cover. Measure the surfaces you intend to line and draw a cutting plan using the actual roll width.
For example, suppose one wall measures 2.4m long by 1.5m high. A 1.5m-wide roll needs a 2.4m length to cover that rectangle before any fitting allowance. Two such walls need 4.8 linear metres. That calculation includes neither the roof nor the ends.
Allow for overlaps and attachment according to the fitting instructions. Decide where each join will sit on the frame, and make separate pieces for opening panels. Keep useful offcuts for small gaps rather than buying a large excess without a plan.
For an aluminium frame, greenhouse insulation clips hold the material in the glazing bars. Match the clip to the channel before ordering a whole pack. Keep the lining secure enough that it cannot drop onto plants or nearby heating equipment.
Keep light, ventilation and access working
Clean the glazing before fitting insulation, then keep the door, handles and vents usable. A lining that must be dismantled whenever you want fresh air soon becomes a nuisance.
On milder days, ventilate to clear damp air. Space pots so leaves are not packed into a wet mass, remove dying foliage and check the compost before watering. Plants resting in cool conditions usually need much less water than they did in summer. The RHS winter greenhouse advice gives useful guidance on ventilation and overwintering.
Check the temperature where the plants stand. A warm afternoon reading can hide a very cold night; a min/max thermometer records the extremes between resets. Keep it shaded, clear of wet glazing and away from the direct output of a heater.
Where heating is used, leave the heater’s specified clearances and ventilation unobstructed. Follow its instructions when positioning any plastic or fleece nearby.
When a smaller protected area is enough
If only one bench holds tender plants, consider screening off that part of the greenhouse. You can then concentrate any heating there while leaving more light for plants elsewhere. The RHS greenhouse-heating guide describes this approach.
Keep an accessible opening for watering and inspection, and put the thermometer inside the protected area. Group plants with similar winter requirements together so the least hardy plant does not dictate how you manage the entire greenhouse.
For containers staying outdoors, use the fleece or bubble wrap for pots guide; wrapping a pot and lining a greenhouse protect different parts of the growing environment.
When the lining is no longer needed, take it down carefully, clean it as directed and dry it before storage. Label the pieces by position. Refitting “left wall” is much quicker than trying a pile of almost-matching rectangles next autumn.
