There is a moment every autumn when the evenings turn sharp and you start worrying about the plants still out in the greenhouse. A little insulation is the cheapest, simplest way to hold on to a few precious degrees, keep the frost off tender plants, and knock a chunk off your winter heating bill. Done well, it can extend your growing season by several weeks at each end of the year, and even keep an unheated greenhouse frost-free through a mild British winter.
The trouble is that “greenhouse insulation” covers everything from proper horticultural bubble wrap to fleece kits, thermal screens and a handful of fiddly clips. We have pulled together the options that actually work for UK greenhouses, with honest notes on where each one shines and where it falls short. Whether you have a small aluminium lean-to or a big walk-in, there is a sensible choice here for you.
Now is the ideal time to buy. Late summer is when the good horticultural bubble sells out, and fitting it on a dry, still day in early autumn is far easier than wrestling with it in a November gale. If you have just bought a new greenhouse, this pairs naturally with our guides to the best greenhouses and the best greenhouse staging and shelving.
Why insulate a greenhouse at all?
Glass and single-skin polycarbonate are poor insulators. On a cold, clear night, heat radiates straight out and the temperature inside can drop almost as low as it is outside. Adding a layer of insulation traps a cushion of still air against the glazing, which dramatically slows that heat loss. In a heated greenhouse this can cut running costs by up to around half, because your heater is fighting the cold far less often. In an unheated one, it can be the difference between overwintering your fuchsias and geraniums successfully or losing them to a single hard frost.
Insulation also cuts down draughts, protects against wind chill, and gives you a warmer space for early seed sowing in spring. The trade-off is light: any insulating layer reduces the amount of light reaching your plants, so the aim is to hold heat without plunging the greenhouse into gloom. That balance is exactly why horticultural-grade materials, with better clarity and UV protection, are worth the extra over cheap packaging offcuts.
What to look for
A few things separate insulation that lasts several winters from a false economy that turns brittle and yellow after one:
- Horticultural grade, not packaging bubble wrap. Proper greenhouse bubble is UV-stabilised so it does not go brittle and cloudy in sunlight. Standard packaging wrap is cheaper but rarely survives a full season outdoors.
- Bubble size. Larger 20-30mm bubbles trap more air and insulate better; small 10mm bubbles let through a little more light and cost less. Many gardeners use large bubbles on the roof and north side, and smaller ones where light matters most.
- Triple-laminated construction. Two skins of film sandwiching the bubbles are far tougher than a single skin and resist splitting on sharp aluminium edges.
- Light transmission. Clear, high-clarity film keeps plants growing through winter; cheaper cloudy material can leave things leggy and pale.
- The right fixings. Bubble wrap is only as good as the clips holding it up. Aluminium-frame greenhouses need push-in insulation clips; timber frames just need a staple gun.
Greenhouse insulation at a glance
| Product | Type | Best for | Guide price |
| Elixir Gardens 25mm Triple-Laminated Bubble + Clips | Bubble wrap kit | Best all-rounder | around £30-45 |
| Harrod Horticultural 20mm Bubble Wrap | Premium bubble roll | Long-term durability | around £30-50 |
| Elixir Gardens 10mm Bubble Insulation | Budget bubble roll | Maximum light / small spaces | around £12-25 |
| Gardening Naturally Fleece Insulation Kit | Fleece + clips kit | Quick, easy fit | around £15-25 |
| Greenhouse Stores 30mm Professional Bubble | Heavy-duty bubble roll | Cold, exposed sites | around £25-45 |
| Push-in Greenhouse Insulation Clips (pack) | Fixings | Aluminium frames | around £5-9 |
| VEVOR / generic horticultural bubble roll | Budget bulk roll | Large greenhouses on a budget | around £15-30 |
Prices vary with roll length and greenhouse size, so treat these as a rough guide and measure your greenhouse before you buy. A quick way to estimate: measure the total glazed area and add around 10-15% for overlaps and the door.
The best greenhouse insulation for 2026
1. Elixir Gardens 25mm Triple-Laminated Bubble Insulation with clips – best all-rounder
If you want one product that does the job properly without overthinking it, this is our pick. It is genuine horticultural-grade bubble with large 25mm bubbles for strong insulation, triple laminated so it stands up to sharp frame edges, and UV-tolerant so it should last several seasons rather than crumbling after one winter. The versions that come bundled with a generous pack of fixing clips are the ones to look for, because they save you a separate order and get you fitted in an afternoon.
It comes in a range of widths and lengths, so you can match it to a small 6×4 greenhouse or a larger walk-in. The 25mm bubbles do dim the light a touch more than thinner film, which is a fair trade for the extra warmth over winter. For most UK gardeners heating a greenhouse or trying to keep one frost-free, this is the sweet spot of price, performance and durability.
Pros: excellent insulation, tough triple-laminated build, clips included, several sizes. Cons: large bubbles reduce light slightly; you will still need a staple gun for timber frames.
2. Harrod Horticultural 20mm Greenhouse Bubble Wrap – premium durability
Harrod is a trusted British horticultural name and its 20mm bubble wrap is a cut above in build quality. It is double laminated, UV stabilised and offers noticeably better light transmission than budget rolls, which matters if you are trying to keep plants growing rather than just ticking over. Fitted correctly, Harrod reckons it can keep an unheated greenhouse frost-free and cut heating costs by up to around half in a heated one.
You pay a premium for the clarity and longevity, and it is sold as a roll so you will want clips separately for an aluminium frame. If you plan to leave your insulation up for several winters and want the best light levels, it is well worth the extra.
Pros: excellent clarity, strong laminated build, long lifespan. Cons: pricier; clips not included.
3. Elixir Gardens 10mm Bubble Insulation – best for light and small greenhouses
Not everyone needs the thickest bubble going. In a small greenhouse, or where you are growing light-hungry salads and early seedlings through winter, the 10mm version is a smart choice. The smaller bubbles let through more light while still trapping a useful layer of air, and it is the cheaper option per metre. It is the same UV-tolerant horticultural film, just a lighter-duty weight.
It is a touch less robust than the 25mm, so handle it carefully around sharp edges, but for a modest greenhouse or a cold frame it does the job nicely and keeps the space brighter.
Pros: better light, low cost, easy to handle. Cons: less insulating than thicker bubble; thinner film is a little more prone to tearing.
4. Gardening Naturally Greenhouse Insulation Fleece Kit – easiest to fit
Bubble wrap is not the only game in town. These fleece kits include a full sheet of 30g horticultural fleece plus corner clips sized to fit most aluminium frames, so everything you need arrives in one box. Fleece is light, breathable and quick to hang, and it is a great choice if you find bubble wrap awkward or you want something you can put up and take down easily.
Available in common sizes like 6×6, 8×6 and 10×8, it is aimed squarely at typical UK garden greenhouses. Fleece insulates less than thick bubble and lets through less light, so it suits overwintering hardy plants and frost protection rather than active winter growing. For a no-fuss, budget-friendly layer, it is hard to beat.
Pros: complete kit, very quick to fit, breathable and reusable. Cons: less insulating than thick bubble; reduces light more than clear film.
5. Greenhouse Stores 30mm Professional-Grade Bubble – for cold, exposed sites
If your greenhouse sits in an exposed, frost-pocket garden, the heavy 30mm professional bubble is the warmest option here. Those large bubbles trap the most air of any product on our list, and the UV-stabilised film is engineered to resist going brittle. It is the closest thing to double glazing you will get from a roll of insulation.
The downsides are predictable: it dims the light the most, and it is bulkier to fit and store. But for keeping a heated greenhouse economical through a hard winter, or protecting an unheated one in a cold part of the country, the extra insulation earns its keep.
Pros: warmest insulation, very durable, great for exposed gardens. Cons: reduces light most; bulky to handle.
6. Push-in Greenhouse Insulation Clips – the fixings that make it work
These are the small but essential heroes of any aluminium greenhouse insulation job. The push-in clips slot into the frame’s glazing channel and grip the bubble wrap with a small washer, so you can put insulation up and take it down each year without damaging anything. Buy a generous pack – you always need more than you expect, especially around the door and roof.
If your bubble wrap kit already includes clips you can skip these, but a spare pack is cheap insurance. Timber-framed greenhouses do not need them – a staple gun does the job.
Pros: cheap, reusable, essential for aluminium frames. Cons: only fit certain frame profiles, so check yours; not needed for timber.
7. VEVOR / generic horticultural bubble roll – best for big greenhouses on a budget
For a large greenhouse where you need a lot of square metres and do not want to spend a fortune, the bigger budget bulk rolls make sense. They are horticultural-grade UV bubble sold in long lengths, so the cost per metre drops. Quality is a step below the premium British brands and the clarity is not quite as good, but for insulating a big space affordably they are a practical choice.
Just check the listing carefully to make sure you are buying UV-stabilised horticultural film and not repackaged packaging wrap, which will not last outdoors.
Pros: cheap per metre, good for large areas. Cons: variable quality; check it is genuine horticultural grade.
How to fit greenhouse insulation
Fitting bubble wrap is a straightforward afternoon job. Choose a dry, still day – trying to handle a sheet of bubble in the wind is a fool’s errand. Start by giving the glass a clean, inside and out, so you keep as much light as possible.
For an aluminium frame, push the insulation clips into the glazing bars first, then hook the bubble wrap over them, working from the top down and overlapping each strip slightly. Keep it taut so condensation runs down rather than pooling. For a timber frame, simply staple the bubble to the wooden bars. Leave the door and any vents free to open, and insulate them separately with an offcut so you can still ventilate on mild days.
Ventilation matters more than people expect. A sealed, insulated greenhouse gets damp, and damp plus mild winter temperatures is a recipe for grey mould. Open the vents or door for an hour on milder, drier days to keep the air moving.
Insulation plus heating: the winning combination
Insulation and a heater work best together. On its own, insulation slows heat loss but cannot add warmth, so in a hard frost an unheated greenhouse will still eventually drop below freezing. Pair your bubble wrap with a thermostatic greenhouse heater and the two work in tandem: the insulation keeps the heat in, so the heater runs far less and costs far less to keep frost at bay. If you are weighing up heating options, see our guide to the best greenhouse heaters.
A cheap max-min thermometer is a worthwhile add-on too. It tells you exactly how cold your greenhouse actually gets overnight, so you can judge whether your insulation alone is enough or whether you need to switch a heater on.
Frequently asked questions
Does greenhouse bubble wrap reduce light too much?
A little, yes – any insulation costs you some light. Clear, high-clarity horticultural film with smaller bubbles keeps the greenhouse brightest, while thick 30mm bubble insulates best but dims the most. For winter, most gardeners accept a small drop in light in exchange for the warmth. In spring you simply take it down.
Can I use normal packaging bubble wrap?
You can in a pinch, but it will not last. Packaging bubble is not UV-stabilised, so it turns brittle, cloudy and useless after a season in the light. Horticultural bubble costs a little more but survives several winters, so it usually works out cheaper in the long run.
When should I put insulation up and take it down?
Fit it in mid to late autumn, before the first hard frosts – late September to October is ideal in most of the UK. Take it down in spring, around March or April, once the risk of hard frost has passed and your plants want maximum light for the growing season.
How much do I need?
Measure the total glazed area of your greenhouse and add around 10-15% for overlaps and the door. Buying a kit sized to a standard 6×4, 8×6 or 10×8 greenhouse takes the guesswork out of it.
Our verdict
For most UK gardeners, the Elixir Gardens 25mm triple-laminated bubble insulation with clips is the best all-round choice: tough, genuinely insulating and ready to fit out of the box. If you want the best light and longest life and do not mind paying more, the Harrod Horticultural 20mm bubble is superb. For a quick, budget-friendly layer, the Gardening Naturally fleece kit is the easiest to live with, and gardeners in cold, exposed spots should reach for the heavy 30mm professional bubble.
Whichever you choose, get it fitted before the first frost, pair it with a thermostatic heater if you are growing through winter, and remember to ventilate on mild days. A few pounds of insulation now can save you far more in heating – and heartbreak – over the months ahead.
