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5 reasons to buy a polytunnel this season with Polycrub

By Sophie King
29th July 2022

Under cover structures can be a real game-changer on the plot, and polytunnels are an ever-popular choice. But why buy a polytunnel? You might be wanting to grow fruit and veg for longer than you would be able to outdoors, or you may be on the hunt for the best polytunnel for a windy site.

Nortenergy, the Polycrub company, is the designer and only supplier of the award-winning Polycrub. The company is a trading arm of Northmavine Community Development Company (NCDC), a charity that works alongside local people to regenerate and develop Northmavine.

A Polycrub is a polytunnel/greenhouse hybrid designed to cope with harsh environments, as experienced in places like Shetland. The company is based in Northmavine, Shetland and is a successful social enterprise. Here, we take a look at some key features of the Polycrub that show just how great growing in polytunnels can be.

Grow more for longer

The Polycrub concept began as an NCDC community project in 2007, when folk in Northmavine were keen to reduce food miles and grow more fresh produce locally, undercover. In addition, folk wanted to find a way to extend what is an incredibly short growing season in Shetland. The community couldn’t find a polytunnel that would withstand Shetland gales, long-term, so they developed their own!

Beneath the cover of a polytunnel, a wide variety of microclimates can be created to suit the crops you wish to grow. The double-layer construction of the Polycrub cover panels help to retain heat and distribute it more evenly. Insulation values are good, and this, along with the protection offered to plants, goes a long way towards increasing the length of the growing season, especially in cooler climates. The black hoops also have a good thermal capacity and store up heat during the day and disperse it at night, acting like a natural storage heater. This reduces the need for electric heating, saving money and energy.

Protect against the elements

Snow, wind and ice can’t torment your crops when they’re protected under cover! Polytunnels offer a fail-safe way of keeping your edibles away from frosts and other unsavoury conditions so that they remain unaffected by dramatic weather changes.

Redundant materials from the aquaculture industry were incorporated into the design, and thick polycarbonate was chosen as the external covering – a fantastic barrier against the outside world. 12 community structures were built in Northmavine, and each building was split into shared, undercover growing plots. This was to be the end of the project, but once the community structures were complete, they attracted lots of interest from others who were keen to buy the product.

NCDC set up the Polycrub social enterprise and developed a range of Polycrubs. Polycrubs have structural accreditation to windspeeds of 120 miles per hour, if built to spec, and are sold in kit form throughout the UK and as far away as the Falklands. Take that for an effective wind breaker!

Keep pests out

It can be disheartening when your crops are eaten by pests after spending hours of hard work and dedication growing them. That’s where polytunnels come to the rescue: they create a physical barrier against larger pests on the plot, from birds to deer. No access means no munching! You might also consider weeds a form of pest – and rightfully so – but under the cover of a polytunnel, these are a lot less likely to spread and wreak havoc on your growing space.

The best light

The sheeting around a polytunnel can really make a difference – it allows light in much the same way as a greenhouse and, in the case of the Polycrub, makes the light the best quality it can be for your fruit and veg. The Polycrub cover is UV-protected, meaning that the most harmful of the sun’s light cannot degrade the sheeting. The light distribution is fantastic and, as it passes through the polycarbonate, it becomes more diffuse, meaning it penetrates areas that light coming through the glass does not.

Great air flow

It’s easy to overlook the importance of ventilation when you’re growing under cover, but all good polytunnels should have the option to allow air flow into the structure. This helps to prevent plants from overheating and keep humidity levels under control so that pests and diseases aren’t invited to spread all around the place. Airflow is also crucial for effective photosynthesis and pollination. Ventilation in the Polycrub is achieved via the combination of doors and/or windows installed.

In 2021, the Polycrub company scooped a national award in the VIBES Scottish Environment Business Awards. It was one of four companies to receive an outstanding achievement award in recognition of its commitment to tackling environmental impacts and reducing carbon emissions. To find out more, go to

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