Greenhouse vs Polytunnel UK: Which Is Best for Your Garden?
Every UK gardener who wants to grow more than the season allows eventually faces the same choice: do you buy a greenhouse or a polytunnel? Both extend your growing year, protect crops from rain and cold, and let you raise seedlings weeks earlier. But they are very different structures, and the right pick depends on your budget, your space, and how windy your garden gets.
In this versus guide We compared the two side by side across the factors that actually decide the argument: upfront cost, heat retention, wind resistance, lifespan, and how much growing room you get for your money. I've also reviewed the best-selling options in the UK in both camps so you can see exactly what your budget buys.
- A polytunnel costs roughly a third of a comparable greenhouse and gives you more growing space per pound - the Outsunny Walk-In Polytunnel 4x2m is a strong budget start at about £65
- A greenhouse holds heat 15-85% better depending on glazing, which means an extra few degrees of frost protection through UK winters
- Wind is the number one killer of polytunnels - a rigid structure like the Outsunny 6x6ft Polycarbonate Greenhouse shrugs off gusts that would lift a plastic cover
- Glass and polycarbonate panels last decades, while a polytunnel cover needs replacing every 4-6 years at £30-£80 a go
- If your main goal is a cheap way to grow more veg, buy a polytunnel first; if you want a permanent, all-weather structure, save for a greenhouse
Quick Comparison: Greenhouse vs Polytunnel
| Feature | Greenhouse | Polytunnel |
|---|---|---|
| Price Range | £200-£500+ | £60-£150 |
| Growing Space per £ | ⭐⭐⭐ Moderate | ⭐⭐⭐⭐⭐ Excellent |
| Heat Retention | ⭐⭐⭐⭐⭐ Excellent | ⭐⭐⭐ Good |
| Wind Resistance | ⭐⭐⭐⭐ High | ⭐⭐ Low without anchoring |
| Lifespan | 20+ years | 4-6 years (cover) |
| Installation | Needs a level base, hours of work | Afternoon job, sits on grass |
| Planning Permission | Sometimes needed (size/position) | Usually exempt, check rules |
| Best For | Tender plants, year-round growing, permanent structure | Maximising veg space on a budget |
Greenhouses - The Permanent Choice
A greenhouse is a rigid, glazed structure with an aluminium or timber frame and glass or polycarbonate panels. It's the traditional option for good reason: it keeps heat in far better than a polytunnel, handles wind without drama, and lasts decades if you look after it.
Heat retention is the biggest difference. Twin-wall polycarbonate panels trap an insulating layer of air, and even single-glazed glass holds warmth better than a plastic skin. That translates to an extra few degrees on cold nights, which is often the difference between a tender plant surviving February and not.
The Outsunny 6x6ft Polycarbonate Greenhouse (around £230) is the best-selling choice for UK gardens and a great first greenhouse. The 6x6ft footprint fits most plots without dominating them, the dark green aluminium frame resists corrosion in damp British conditions, and the slide door plus opening window give the airflow that stops seedlings damping off. Twin-wall 4mm polycarbonate glazing keeps night temperatures noticeably higher than a polytunnel of the same footprint.
If you want to spend less but keep the rigid-frame benefits, the GARDEBRUK 6x6ft Anodised Aluminium Greenhouse (around £234) is the one to compare. It uses the same twin-wall polycarbonate panels but with an anodised aluminium frame that never needs painting. The sliding door is smooth and the built-in skylight vents hot air automatically, which matters in a UK summer where an unvented greenhouse can hit 40°C.
At the premium end, the Palram Canopia Harmony 6x6 (around £212) is the name UK gardeners trust for longevity. Palram builds commercial-quality polycarbonate panels and powder-coated aluminium, and the Harmony's rust-proof frame and 10-year warranty are the reason it outsells cheaper rivals over time. You pay for the brand, but you get a structure that will outlast three polytunnel covers.
For gardeners who want a growing space and a workbench in one, the Outsunny 6x6ft Greenhouse with Base and Raised Bed (around £194) bundles a galvanised base and an integrated planting bed, so you can fill it with soil and plant straight in rather than potting everything up. The temperature-controlled window opens automatically when it gets too hot inside, which is a genuinely useful feature during a British heatwave.
Pros of a Greenhouse
- Better heat retention - 15-85% more than a polytunnel depending on glazing, giving real frost protection
- Wind resistant - rigid panels don't flap, lift or tear in storms
- Long lifespan - panels and frames last 20+ years with basic care
- Looks better - a glazed greenhouse is a garden feature, not an eyesore
- Holds shelves and staging - glasshouses are built to carry weight
Cons of a Greenhouse
- Expensive - a usable 6x6ft model costs £200-£500 before the base
- Needs a level base - concrete or paving slabs add cost and labour
- Longer to assemble - expect a full day for a 6x6ft model
- Can overheat - without ventilation it bakes on sunny days
Polytunnels - The Budget Workhorse
A polytunnel is a galvanised steel hoop frame covered with a single sheet of UV-stabilised polythene. It's the structure commercial growers use because it delivers the most growing space per pound of any option. A £65 polytunnel can cover more soil than a £300 greenhouse, which is why veg growers love them.
The trade-off is that a polytunnel is a tent, not a building. The cover flaps in wind, tears eventually, and lets heat escape faster at night. If you anchor it properly it's perfectly usable for the vast majority of UK gardens, but it needs more care than a greenhouse.
The Outsunny Walk-In Polytunnel 4x2m (around £65) is the pick for first-time buyers. The 4x2m footprint gives you proper room to walk in and work, the galvanised steel frame is far sturdier than the cheap plastic alternatives, and the zipped roll-up door plus eight mesh windows provide the airflow that stops condensation dripping on your plants. For the price of two nice dinners you get a season-extending growing space.
For a smaller budget or a tighter corner, the Outsunny Walk-In Polytunnel 4.5x3x2m White (around £65) is the value king. The white cover reflects more light and heat back onto the plants than a clear one, and it looks cleaner against a fence line. Its roll-up door and windows mirror the bigger model, so you're not losing ventilation for the sake of saving £79.
If you want a tunnel that feels closer to a building, the VonHaus Polytunnel Greenhouse 3x2m (around £85) swaps the zip door for a proper hinged one you can lock, which keeps children, foxes and curious dogs out of your crops. The heavy-duty PE cover is reinforced at the stress points and the frame includes extra cross-bracing, making it one of the sturdier options in the sub-£103 bracket.
For serious veg growers, the Outsunny Polytunnel 6x3m (around £100) is the sweet spot. At 6m long it holds three decent-sized beds, which is enough to grow salads, tomatoes, beans and winter brassicas all year round. The heavy-duty steel frame and UV-resistant cover are built to stay up for years, and the double roll-up doors at each end create the through-draught that keeps fungal disease at bay.
Pros of a Polytunnel
- Far cheaper - roughly a third of the price of a comparable greenhouse
- More growing space per pound - a £70 tunnel beats a £300 greenhouse on square metres
- Easy to install - most go up in an afternoon with basic tools
- Sits on soil - no concrete base, so you can plant straight into the ground
- Easy to move - you can relocate a small tunnel if your layout changes
Cons of a Polytunnel
- Wind damage - gusts can lift or tear the cover; anchoring is essential
- Worse heat retention - colder at night, so tender plants still need fleece
- Cover wears out - UV damage means replacement every 4-6 years
- Condensation - single-skin plastic drips unless you ventilate daily
- Not covered by insurance - many UK policies exclude polytunnel storm damage
How to Choose the Right Structure for Your UK Garden
Choose a Greenhouse If…
- You want to overwinter tender plants like citrus, olive trees or pelargoniums
- Your garden is exposed and windy, where a polytunnel cover would take a battering
- You want a permanent structure you'll never have to replace
- You have the budget for the structure plus a proper base
- You want the garden to look good as well as grow well
Choose a Polytunnel If…
- You're on a budget and want the most growing space for the least money
- Your priority is veg production, not aesthetics
- You have a sheltered spot or can anchor the frame securely
- You want to plant directly into the soil rather than potting everything
- You're not sure a structure will work in your space and want to try cheaply first
Frequently Asked Questions
Final Verdict
Neither structure is objectively better - they solve different problems. A polytunnel is the fastest, cheapest way to grow more veg and extend your season, and for most home gardeners it's the right first buy. A greenhouse is the permanent upgrade: better heat retention, better wind resistance, and a structure you'll pass on to the next owner.
If you're still deciding, start with the Outsunny Walk-In Polytunnel 4x2m at around £65. It tells you within one season whether a protected growing space transforms your garden, and the money risk is tiny. If the answer is yes and you want it to last decades, trade up to the Outsunny 6x6ft Polycarbonate Greenhouse knowing exactly what you're getting.
Whichever you choose, it pairs well with a cold frame for hardening off seedlings, and both structures earn their keep the moment you sow autumn vegetables under cover.
Sam Baker writes about garden tools and equipment for MyLushGarden, comparing products on specs, owner feedback and market research.
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Last reviewed: August 14, 2026 · Evidence-based content · Contains affiliate links