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Growing polytunnel tomatoes without cooking the crop

Updated: 22 October 2026

The plastic house looks like the shortcut to earlier red fruit. Growing polytunnel tomatoes fails in the same three ways on UK plots: the air sits above about 27°C with the door shut, the bags dry then flood, and a gale forces the cover off because the listing already said it would. The nine structures, with prices in GBP, are on the [polytunnel comparison](/hub/garden-supplies/polytunnel). This page does not re-score them. Peter F. compared RHS crop notes with these cards, and did not run a lab test. A qualifying purchase can earn us a commission at no extra cost to you.

The plastic house looks like the shortcut to earlier red fruit.

Our top picks

Ohuhu Ohuhu 180 × 180 × 200 cm

Best overall

Ohuhu Ohuhu 180 × 180 × 200 cm
8.7/10about £59.99
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VOUNOT VOUNOT 3 × 2 × 2 m

Best value

VOUNOT VOUNOT 3 × 2 × 2 m
8.2/10about £50.49
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Heekcaa Heekcaa mini tunnel, 122 cm

Rank 3

Heekcaa Heekcaa mini tunnel, 122 cm
0.0/10about £16.99
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On this page
  1. 1.A tunnel that is tall enough
  2. 2.Heat and the door
  3. 3.Water, bags, and blossom end rot
  4. 4.Wind in the middle of the crop

A tunnel that is tall enough

Cordon tomatoes need headroom and a door you can walk through. The walk-in soil tents in this set are about 2 m high: VOUNOT at 3 × 2 m, 3 × 3 m and 4 × 3 m, and Outsunny at about 2.5 × 2 m, about 3 × 2 m and about 6 × 3 m. Stake or string the plant and leave space so the cover does not slap the foliage. The Ohuhu 180 × 180 × 200 cm walk-in is also about 2 m high on 3.24 m². Its bullets name tomatoes among other crops. That is a listing claim, not a yield. The Heekcaa mini tunnel at 45 cm high is not a cordon house. Once stems reach for the roof, you are growing into plastic. The VOUNOT shelf growhouse is for pots on four shelves rated 10 kg each. Pots can ripen fruit, but they dry faster than border soil. If you have not chosen soil walk-in, shelves or cloche, fix that on the walk in polytunnel buying guide before you sow.

Heat and the door

RHS ventilation guidance is the figure to keep: open doors and vents on sunny days, because plant damage typically appears above about 27°C. Shade only as much as you need, especially for tomatoes. First Tunnels crop notes talk about stress around 30–32°C. That is their wording, not a second threshold to average with the RHS line. Use 27°C as the cited damage point and open earlier rather than later. These amazon tents do not show ridge vents or automatic openers. You have roll-up or zip doors and side mesh. On a bright May or June morning, open before the air climbs. Mesh alone may not be enough if the door stays shut. A closed green cover on a hot day is a cooker. Plastic versus glass for winter and light belongs on polytunnel vs greenhouse.
Ohuhu Ohuhu 180 × 180 × 200 cm

Testsieger

Ohuhu Ohuhu 180 × 180 × 200 cm
8.7/10about £59.99
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Water, bags, and blossom end rot

Steady moisture is the other half of the crop. RHS blossom end rot advice treats the black base as uneven watering, not a disease: calcium fails to reach the fruit when the compost swings from dry to soaked. Pots and grow bags suffer more than border soil. The same swing, drought then flood, cracks the skin. Water so the root zone never fully dries, especially in bags on hot plastic floors. Feed from first flowers if you follow a tunnel maker’s crop sheet. Do not turn a bicarbonate spray tip from a commercial PDF into a treatment plan. Border soil under a trenched walk-in is kinder if you can keep the cover on. Bags on the shelves are convenient and thirsty. Uneven water shows on the fruit before it shows on a star rating. Greenback from excess light and heat is another RHS fault when shade is too late and the door stayed shut.

Wind in the middle of the crop

Plan the site as if a gale warning will arrive in July. Several listings tell you to remove the cover in wind or not to leave the tent up in heavy weather. The VOUNOT 4 × 3 × 2 m card is explicit: trench the base, and still remove the cover when there is wind. Outsunny cards limit light wind and rain or say the structure is not for bad weather. If you strip the sheet mid-crop, cordons lose their climate overnight. Anchoring steps sit on how to anchor a polytunnel. A sheltered plot with a skirt that stays buried is part of the tomato plan. RHS notes blight is more often an outdoor problem than a greenhouse one. That is a relative risk line, not a guarantee. Keep air moving on damp days as well as hot ones.

Common questions

Can I grow cordon tomatoes in these walk-in tents?
Yes in the about 2 m walk-ins if you train them and keep the cover off the leaves. Not in the 45 cm Heekcaa cloche once plants are tall.
When do I open the door?
On sunny days, early enough that the air does not sit above about 27°C. These tents rely on doors and mesh, not automatic roof vents.
What temperature starts to damage plants?
RHS cites damage typically above about 27°C. Do not average that with a maker’s higher stress band into one number.
Why do fruit split or rot at the blossom end?
Uneven water. Bags and pots swing faster than border soil. Heat with a shut door makes both faults worse.
Are grow bags a good idea in a hot tent?
They work if you water steadily. They fail faster than border soil when you miss a day in heat.
What if a gale means the cover has to come off mid-crop?
Expect a climate shock. Site the tent where you can keep the sheet on within the listing’s limits, or accept an open frame after strip-down.
Do these tents have ridge vents or automatic openers?
Not in this set. Plan on manual doors and side mesh every bright day.

Related pages

Greenhouse window opener comparison

Garden polytunnel

Best polytunnel UK: pots, soil tent and skip rules

Walk in polytunnel buying guide: type, size, rules

How to anchor a polytunnel in the UK: skirt and wind

Polytunnel vs greenhouse: summer crop or frost-free

Sources

Public UK sources for this comparison. Prices, stars and review counts are the amazon.co.uk listings in this set, captured 19 October 2026. Page updated 22 October 2026.

  1. Planning Portal: outbuildings (retrieved 22 October 2026)
  2. GPDO 2015 Class E (retrieved 22 October 2026)
  3. mygov.scot: shed, garage or greenhouse (retrieved 22 October 2026)
  4. GOV.WALES: planning permission for outbuildings (retrieved 22 October 2026)
  5. RHS: choosing greenhouses (retrieved 22 October 2026)
  6. RHS: ventilation and shading (retrieved 22 October 2026)
  7. Northern Polytunnels: EasyBuild (retrieved 22 October 2026)
  8. Consumer Rights Act 2015, section 22 (retrieved 22 October 2026)