Both let you start sowing earlier, grow tomatoes and peppers in a British summer, and keep picking salads later into autumn. A polytunnel gives you more space for the money. A greenhouse is tidier, sturdier and lasts longer.
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The RHS says an unheated greenhouse extends the growing season at both ends. In summer it's the place for tomatoes, peppers, cucumbers and aubergines. In spring it brings on seedlings; in autumn and winter it can keep hardy salads going.
The RHS says heated greenhouses are rarely cost effective, so the figures here assume no heating.
If you mainly want earlier salads and somewhere to harden off seedlings, a low growhouse or cloche may be all you need, and costs far less. Try that first if you're not sure.
| Polytunnel | Greenhouse | |
|---|---|---|
| Kit price, small walk-in | From £442 (6 ft wide, 8 ft long) | £629 to £840 (6 ft by 8 ft) |
| Space for the money | More growing room per pound | Less, but neater |
| Cover | Polythene sheet, replaced every few years | Glass or polycarbonate, lasts much longer |
| Wind | Must be anchored well; the cover can tear | Needs a firm, level base; lighter models aren't for exposed spots |
| Looks | Practical, allotment-style | Tidier in a small garden |
| Best for | Growing a lot, on a budget, with room to spare | A smaller garden, and somewhere to sit among the tomatoes |
Kit prices from the products below, checked 4 November 2026. Bases, delivery, groundwork and installation are extra.
The price on the page is rarely the whole bill. One greenhouse we looked at listed a base at £89 and installation at £510 on top of the £629 kit, with soil, gravel and groundwork not included. Another quoted a £179.99 base and a 30 to 40 working-day wait. For a polytunnel, the cover, doors, base rails and anchoring options can add a lot to the starting price. Get a full delivered quote before you compare.
In England, a greenhouse in the back garden of a house is usually allowed without planning permission, under "permitted development" rules for outbuildings. The Planning Portal sets out the main limits:
You need permission if the home is a listed building, and different rules apply in conservation areas, national parks and other protected land. Flats and maisonettes don't have these allowances, and some homes have had them removed. The rules don't mention polytunnels by name, so don't assume one is exempt because it's plastic.
Scotland, Wales and Northern Ireland have their own rules. Wherever you are, if you're unsure, ask your council's planning department before you buy.
Ranked by size, from a first step to more room. Prices checked 4 November 2026; starting prices before options. Specs are from the shops' listings.
Not a walk-in tunnel: a 3 m long, 1 m high cover you tend through zipped openings. It brings on salads and young plants earlier, and tells you whether you'll use a bigger one. Price includes mainland delivery; the shop doesn't deliver to Northern Ireland.
A walk-in tunnel 1.83 m wide and just over 2 m high, from 8 ft long. £442 is the starting price for the shortest length. The cover, doors and anchoring you choose change the total, so build the full quote before comparing.
Wider at 2.44 m, from 10 ft long, with 28 mm steel hoops and foundation tubes included. Its standard 150-micron cover has a 4-year warranty against sun damage; thicker covers and extras cost more.
Prices checked 4 November 2026, kit only. Bases, groundwork and installation extra. Specs are from the shops' listings.
A 6 ft by 8 ft aluminium greenhouse with toughened glass and one roof vent. The shop lists a base at £89 and installation at £510, and the groundwork isn't included in either.
About the same footprint, with a low door threshold, two roof vents and a black frame. Delivery was quoted at 30 to 40 working days, and a base costs extra.
Bigger at 6 ft by 10 ft, glazed with clear polycarbonate rather than glass. The shop says it's not suitable for windy or exposed positions, so it's for a sheltered garden.