Polytunnel or greenhouse — the question shows up in every UK growing forum. Both keep the rain off, both extend the season, both turn a serious gardener into a year-round one. But they're different tools for different situations, and the wrong choice costs years of frustration plus the eventual cost of replacement.
This piece is the seven questions to answer before deciding, with practical detail on where each option genuinely wins. We sell wooden greenhouses so we have a horse in the race — but for some uses (large-volume veg, tight budget, allotment-only) the polytunnel is genuinely the better answer. We'll say so where it applies.
Written by Alex Goldgewicht, founder of Waldenhaus. Reviewed by the Waldenhaus product team. Last updated 7 May 2026.
What each one actually is
A polytunnel is a galvanised steel hoop frame covered with a single-skin polythene sheet (typically 720–800 gauge horticultural polythene with a UV-stabilised inner surface). The cover is tensioned over the hoops and anchored at the ground line. Internal volume is large for the cost — a 6×4 m polytunnel at £700 gives you 24 m² of covered growing space.
A wooden greenhouse is a rigid timber-framed structure with glass or polycarbonate panel glazing, mortise-and-tenon jointed (in mid-tier and above), with a permanent door, vents, and a defined service life of 15–30 years. Internal volume is smaller per pound spent — an 8×10 ft NORDIC at £1,599 gives 7.5 m² of covered space.
Different physical tools, different commercial logic, different right answers depending on the situation.
The seven questions
Q1. How much space are you trying to cover?
Polytunnels scale much cheaper per square metre. A 6×4 m polytunnel (24 m²) costs roughly £700 for a basic kit including the cover. A wooden greenhouse covering the same internal area would be around the 8×24 ft mark — well above £2,500 in mid-tier construction.
If you need 20+ m² of covered growing space and budget is bounded: polytunnel wins by cost-per-m² alone. If you need 5–15 m²: the absolute gap narrows; the greenhouse case rests on lifespan, appearance, rigidity and crop control rather than lowest £/m².
Rough threshold: polytunnel becomes economically dominant above ~15 m² target footprint.
Q2. How long do you plan to keep it?
The polythene cover on a polytunnel is the consumable part. Realistic UK service life:
- 3–5 years for a basic horticultural cover in an exposed site
- 5–7 years for a long-life cover (anti-fog, anti-condensation, UV-stabilised) in a sheltered site
Cover replacement cost: £150–£400 depending on size. Replacing the cover is a job for two adults on a still day; not difficult but not trivial.
A wooden greenhouse's polycarbonate glazing typically lasts 15–25 years before any panel replacement. The frame, with proper maintenance, lasts 20–30+ years.
Cost per year over a realistic 20-year ownership horizon, normalised by area covered:
- Polytunnel 6×4 m (24 m²): £700 initial + 4 cover replacements × £250 = £1,700 / 20 yr = £85/yr / £3.50 per m² per year
- Wooden greenhouse 8×20 ft (~14.9 m²): £1,899 initial / 20 yr = £95/yr / £6.40 per m² per year
The polytunnel is genuinely cheaper per square metre for bulk-growing scale. But you're trading reliability for cost — every cover replacement is a half-day job that can't be put off forever.
Q3. How exposed is your site?
This is where polytunnels run into real trouble in the UK. The single-skin polythene cover is vulnerable to:
- Wind ripping — Force 8 storms (39–46 mph sustained) regularly damage covers; gusts above 60 mph can detach a cover entirely
- UV embrittlement — covers gradually become brittle from year 3 onwards; a brittle cover that takes a sudden wind impact tears more easily
- Snow load — polytunnels need active snow clearance during heavy falls; the cover sags and can tear under sustained weight
- Bird damage — pecking starlings and crows occasionally puncture covers, especially during berry season
A well-built wooden greenhouse with screw-fixed polycarbonate has come through Force 9 conditions (47–54 mph) without intervention in customer reports we've seen, when properly anchored. Polycarbonate with a co-extruded UV-stabilising layer holds light transmission much better than uncovered or generic poly through long sun exposure, and snow load is mostly carried by the frame rather than the glazing. Full storm performance detail is in our wind-resistant greenhouse guide.
For exposed sites in the top 25% of UK wind exposure (Pennines, west-coast Scotland, north Yorkshire moors, Cornish coast), a polytunnel is genuinely difficult to keep running long-term. A greenhouse is the lower-stress choice.
For sheltered sites (suburban gardens, walled allotments, urban back yards): polytunnel wind risk is manageable.
Q4. What's the look you want in your garden?
Polytunnels are agricultural-looking. Functional, productive, but a polytunnel reads as "small-holding equipment" rather than "garden architecture". Some gardens have the space and the aesthetic for that; others don't.
A wooden greenhouse reads as a permanent garden building — closer in visual category to a shed or summerhouse than to farm equipment. In smaller gardens, walled gardens, or properties where the garden is visible from the house, the visual difference matters substantially.
This isn't a question with a right answer; it's a personal decision. But it's worth being honest about. If your garden is "the productive end of a small-holding", a polytunnel fits; if it's "the back of a Victorian terrace", probably not.
Q5. What are you actually growing?
Different crops favour different structures:
Polytunnel-favouring crops:
- Soft fruit (raspberries, gooseberries, blackcurrants) — the large internal volume suits cane fruit
- Bulk salad and brassica production — large continuous beds are easier in polytunnel form
- Cut flowers (dahlias, sweet peas, cosmos for cutting) — vertical room and bed space matter more than light quality
- Pumpkins, courgettes, squashes — they spread, polytunnels accommodate spread
Greenhouse-favouring crops:
- Tomatoes, peppers, chillies, aubergines — these are light-demanding and benefit from the higher light transmission of glass or twin-wall polycarbonate (~85–90%) versus polytunnel polythene (~85% when new, falling to ~65% by year 4 of cover life)
- Tender ornamentals (citrus, brugmansia, plumbago) — they need defined frost-free conditions, more easily achieved in a sealed greenhouse
- Propagation work — better climate control in a smaller volume
- Year-round salad cropping — better thermal stability
The light-quality difference is more material than gardeners often expect. By the third year of a polytunnel cover, light transmission has often dropped 15–20% from new — meaningful for sun-loving crops in marginal British growing months.
Q6. Are you in a position to comply with planning rules?
For most domestic plots in England, both polytunnels and greenhouses are likely to fall within Permitted Development if under 2.5 m at the eaves, covering under 50% of garden area, and not in front of the principal elevation. Scotland, Wales and Northern Ireland have different Permitted Development rules — always check with your local planning authority before ordering.
Special-status sites:
- Listed buildings and conservation areas: Both typically require consent. Polytunnels are sometimes refused on aesthetic grounds where a wooden greenhouse would be approved.
- Allotments: Most sites allow both, but typically with size limits (often max 8 ft × 8 ft) and material rules. Some site committees explicitly restrict polytunnels above certain sizes; restrictions on wooden greenhouses are less common.
- AONBs and National Parks: Polytunnels above small scale generally receive scrutiny; wooden greenhouses below 2.5 m height usually clear without formal application, but again — check locally.
The pattern: for most UK domestic gardens, neither structure is restricted; the question matters mainly in special-status locations. Always verify with your local planning authority and (for allotments) site committee before ordering.
Q7. How much DIY are you comfortable with?
Polytunnels are inherently more DIY-heavy:
- Cover installation: 4–6 hours, two adults, requires a still day
- Cover replacement (every 3–7 years): same job, repeated
- Door reseating: covers stretch over time and door zips need repairing or replacement
- Anti-condensation drip strip maintenance: annual
- Anchor inspection (especially for ground-screw anchored covers): biannual
Wooden greenhouses are much lower-touch:
- Build: one weekend, two adults, then largely done
- Glazing: install once, replace individual panels only when damaged (rare)
- Door / vent: occasional re-greasing of hinges and vent mechanism
- Timber re-treatment: every 2–3 years (1 hour for an 8×10 ft)
For a hands-on grower who enjoys the physical work, polytunnel maintenance isn't a problem. For a grower who wants the structure to "just work" between maintenance windows, a wooden greenhouse demands less.
Decision matrix
| Your situation | Polytunnel | Greenhouse | Both |
|---|---|---|---|
| 24+ m² target footprint, modest budget | Yes | — | — |
| 5–15 m² target footprint | — | Yes | — |
| Exposed site (top 25% UK wind) | — | Yes | — |
| Sheltered site, suburban garden | — | Yes | — |
| Allotment with 8×8 ft size limit | — | Yes | — |
| Allotment with no size limit, productive focus | Yes | — | — |
| Soft fruit + bulk salad + cut flowers | Yes | — | — |
| Tomatoes, chillies, ornamentals | — | Yes | — |
| Visible from house, neighbours, garden visitors | — | Yes | — |
| Behind the shed at the bottom of a long allotment | Yes | — | — |
| Want one structure that "just works" 20 years | — | Yes | — |
| Want max growing area for the budget | Yes | — | — |
| Serious grower at scale | — | — | Yes (greenhouse for tomatoes/propagation, polytunnel for soft fruit/bulk) |
The "Both" answer is more common among serious gardeners than online discourse suggests. The two structures genuinely solve different problems, and at scale the rational solution is one of each.
Where the choice usually goes wrong
Three patterns we see in customer correspondence and grower forums:
Buying polytunnel for tomato production on an exposed site. Cover lifespan is short, the light loss by year 3 affects fruiting, and the structure is a permanent maintenance burden. A wooden greenhouse handles tomatoes better and outlasts the polytunnel by 3–5×.
Buying greenhouse for bulk allotment cropping. An 8×10 ft greenhouse fills up immediately for someone trying to supply a household with year-round veg. The footprint is too small for the use case; cost-per-m² is too high. A 6×4 m polytunnel covers the same space at a quarter of the upfront cost.
Choosing on cost alone. Polytunnels look cheaper per square metre, so they win the calculator round. But over a realistic 20-year horizon with cover replacements, the cost gap shrinks — and for ambitious crops (tomatoes, chillies), the produce-quality difference favours the greenhouse decisively.
What we'd actually recommend
For the typical UK domestic gardener reading this article — south-of-the-Highlands, suburban or allotment plot, family-of-2-to-4 supply ambition, 15–25 year ownership horizon — a wooden greenhouse in mid-tier construction (the segment where NORDIC at £1,499–£1,899 sits) is the rational answer. It's lower maintenance, looks better in the garden, lasts 3–5× longer between major interventions, and produces better-quality light-demanding crops.
For the serious grower at scale — large allotment, small-holding, 30+ m² growing ambition — a polytunnel for the bulk soft fruit + brassicas + courgettes plus a smaller wooden greenhouse for tomato/pepper/propagation work is often the right combination.
For the budget-bounded beginner — under £400 to spend, want to find out if they like growing — a polytunnel-style hoop kit on an allotment is fine for the first 3 years, replaced with something more permanent once the commitment is proven.
Frequently asked questions
Are polytunnels really cheaper than greenhouses?
Per square metre of covered space, yes — meaningfully. Per growing year of useful life, the gap is much smaller because polytunnel covers are a 3–7 year consumable. For 20-year ownership of equivalent space: polytunnel ~£85/yr, greenhouse ~£140/yr — polytunnel cheaper but not dramatically.
Will a polytunnel survive a UK winter?
Yes, in most situations. Modern horticultural polythene with UV-stabilised inner skin handles 8 winters in sheltered sites, 4–5 in exposed sites. The vulnerable moments are autumn storms (Force 8+) and heavy snow loads — both can damage or destroy covers. Greenhouses with screw-fixed polycarbonate are inherently more weather-tolerant.
Can I heat a polytunnel?
You can, but it's expensive. The single-skin polythene has dramatically higher U-value (worse insulation) than twin-wall polycarbonate, so heating costs roughly 2–3× as much per degree of temperature lift. Most polytunnel growers don't heat; they accept the season-end and re-start in spring.
Do polytunnels need planning permission?
For most domestic UK plots, no — they fall under Permitted Development at typical hobby sizes. Listed buildings, AONBs, conservation areas, and some allotment committees apply stricter rules. Always check with your local planning authority and your allotment site committee before ordering.
Is the light quality really worse in a polytunnel?
Yes, especially after year 2 of a cover's life. New horticultural polythene transmits ~85% of available light (similar to glass); by year 4, transmission has typically fallen to 65–70% as the polythene clouds and yellows under UV. Twin-wall polycarbonate (4 mm CrystalLight™ on NORDIC) holds ~90% transmission for 20+ years with proper UV layer.
Can I put a polytunnel and a greenhouse on the same plot?
Often yes — and this is what serious growers commonly do. Greenhouse for tomatoes, peppers, propagation, ornamentals; polytunnel for soft fruit, brassicas, salad bulk, courgettes. The two complement each other; neither does both jobs well alone.
What about cold frames as a third option?
Cold frames are smaller-scale season-extension tools — useful alongside either a polytunnel or greenhouse, not a replacement for either. Full cold frame coverage is in our cold frame vs mini greenhouse vs full guide.
Choose your NORDIC wooden greenhouse
By size
- 8×6 ft — NORDIC-S £1,499 · patio / starter / small allotment
- 8×10 ft — NORDIC-M from £1,599 · family veg garden sweet spot
- 8×13 ft — NORDIC-L from £1,699 · serious year-round growing
- 8×16 ft — NORDIC-XL from £1,799 · multi-crop with two ground beds
- 8×20 ft — NORDIC-XXL from £1,899 · walk-in / market grower
By configuration
- Lean-to wooden greenhouse · wall-mount, space-efficient
- Polycarbonate greenhouses UK · 4 mm CrystalLight™ glazing detail
Decide before you buy
- Greenhouse Buying Guide UK 2026 · full step-by-step framework
- Wooden Greenhouses overview · the NORDIC range explained
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