The Allotment Polytunnel

Our 2-piece steel tubes are coated with Armourguard which offers up to 20 times the corrosion resistance of pre-galvanised steel tube.
ArmourGuard® is Northern Polytunnels’ newly developed high-endurance tube, combining extraordinary levels of corrosion resistance with the durability of high-strength steel. ArmourGuard® offers up to 20 times the corrosion resistance of an ordinary pre-galvanised tube thanks to its revolutionary zinc, aluminium and magnesium coating.

Environmentally Friendly

ArmourGuard® even protects the environment by reducing the amount of zinc which is used in the manufacturing process compared to fully galvanised steel tubes, and by extending the product life.

50 Years of Exposure without Deterioration

ArmourGuard® is designed not just to survive in the most hostile environments but also to offer extreme longevity. In exhaustive tests carried out by Rotech Laboratories, one of the UK’s leading test houses, ArmourGuard® endured the equivalent of 50 years of exposure to the harshest elements without undue deterioration.

Wide Door Widths as Standard - Our door widths measure 800mm as standard, no 'upgrade' required for your wheelbarrow.

Tanalised timber has been saturated with Tanalith wood preservative under rigidly controlled conditions in a vacuum pressure timber impregnation plant.

The door frames would be expected to last for several years rot free and may even last for more than 10 years, however, due to the nature of the door posts being dug in to the ground, the constant contact with the mud, grass and water does mean they may not last this long.

Both the base rails and door frames wood measure 50mm x 75mm making it a sturdy and strong structure.

Stronger than 3 or 4 section hoops

Hoops that are made from three or four sections are easier to make and more convenient to deliver, however, they are not as strong as a two-piece hoop and often require extra bracing bars to support them.

That is why we only make two-piece hoops on our hobby range of polytunnels.

Choose from either the stanard foundation tube or the Ground Anchor Plate to suit your location and needs.

As our foundation tubes are 2.5mm thick, they are foundations that can be relied upon.

It’s essential for the poly cover to be drum-skin-tight, this stops the polythene from vibrating in the wind, causing it to degrade quickly.

As part of the maintenance of your polytunnel, the cover must be kept tight. If your cover is installed when it is cold it will need tensioning when the temperature rises.

Our cover tensioning system is simple just loosen the collar (A) lift the hoop (B) lift the collar and re-tighten in place.

We build this feature in all our polytunnels as it is essential for the life of the poly cover.

PVC Double Zip Vent Door

A PVC 3in1 door that suits all weather and gardener.

This door comes with 2 heavy-duty zips for ease of access, a Velcroed panel that can be removed partially or entirely to allow as much or as little ventilation as required and two Velcro tabs that secure your door in place out of the way for those long hot summer days.

Wide Door Widths as Standard

Our door widths measure 800mm as standard, no 'upgrade' required for your wheelbarrow.

Screw Anchor Foundation Tubes

By far the most popular method as it removes the need to dig any holes. Suitable with most types, especially clay soils.

Avoid only on ground with a high stone/rubble content, peat souls or loose ground which has been recently disturbed or deeply cultivated. Only takes 1-2 minutes to secure each one in position, a fraction of the time it would take to install ground anchor plates, without the mess or exertion.

Screw anchors also incorporate our unique, polytunnel cover tensioning system, where the hoops are raised (and locked in place) after the cover is attached to achieve a drum-skin-tight finish. The tighter the cover the longer it will last!

Available on the Easy Build range and Hobby Range

Base Plates (for concrete base)

Base plates are only used when fixing onto a solid concrete base or railway sleepers. Supplied with fixing bolts

Available on The Highlander, Easy Build and Hobby range

Traditional Foundation Tubes

Concreting method

The traditional method is to dig a hole (35cm square x 50cm deep) and set the foundation tubes in concrete. A secure method, generally used where screw anchors aren’t suitable.

Driven into the ground

Foundation tubes are knocked in the ground, leaving 35-45cm protruding. This method is usually only used where the polytunnel cover is trenched into the ground.

Available on all our polytunnels.

Ground Anchor Plates - (Ground Anchors)

Generally only used where screw anchors and traditional ‘concreted’ foundation tubes are not the preferred choice. Less secure than other options.

The foundation tubes have a metal plate fastened at the base which sits in the ground in a hole (35cm square x 50cm deep), then backfill with earth. These are suitable when screw anchors can’t be used (e.g stoney ground) and where concreting isn’t an option.

Available on Allotment, Hobby Range and Easy Build range.

Also knows as Widthways Crop Bars

Although often used to hold hanging baskets or to support lateral poles on which to tie up your tomatoes, peas etc, they are more often added to a polytunnel to give it extra strength. Even though we boast that our polytunnels are the strongest available, they give peace of mind during severe, windy storms and also when heavy snow is expected.

They increase the structural strength by at least 20%.

Can be retrospectively fitted to existing polytunnels.

Your basic polytunnel should always have a central ridge bar, but additional ridge bars can be added to either one or both sides of a polytunnel.

They will of course increase the strength a little, but the main use for these is to provide crop support along the length of the polytunnel. They can be positioned and re-positioned to the most convenient place for the crop you are growing.

Roof Vents

Easy to install roof vent, with simple pull-cord operation.

Used to release excessive heat build-up in your polytunnel without having to open the doors. The spring closing design allows it to be closed tight shut when ventilation is not required. Useful in longer polytunnels where heat can build up in the middle, or when the doors need to be closed (e.g. to keep unwanted visitors out).

Simply cut out a 30-35 cm hole in the roof of your polytunnel cover, insert the fan from the inside in a rotating motion, clip on the support bars (sold separately) and it’s done.

Available on all ranges

Drop Down Polytunnel Bench

This drop-down bench is great for potting up in the polytunnel and once you’re done you can simply secure it out of the way. Easily installed in new or existing polytunnels. Several can be linked together to create a continuous bench.

Frame: Galvanised steel Top: Tanalised timber

Staging

Our polytunnel staging kits are a low-cost solution where a full-length bench is required for your polytunnel. We ONLY provide the steel frame, leaving you to provide your own tabletop. Some customers use heavy-duty, galvanised weld mesh, whereas others choose timber slats. Whatever your choice, our staging kits provide the ideal framework on which to grow your potted plants.

Supplied with fasteners for fixing timber slats (Timber not included). Can be installed in new and existing polytunnels.

Free Standing Benching

Easy to assemble flat-pack bench, manufactured from 25mm pre-galvanised steel tube with a steel mesh top.

Supplied with four corner bracing bars to give extra stability. The bench is 1m wide, 0.8m high, and comes in 1.2m long sections, allowing you to create a continuous bench to suit the length of your polytunnel or plant display area.

Size

• Unlimited length (in 1.2m increments) minimum length 2.4m
• Robust design
• Fully galvanised
• 3” x 1” Steel mesh top (3mm diam.)
• Quick self-assembly
• Simple slot together frame

Polythene film: Diffused or Clear?

Light Transmission

• Light transmission is the quantity of light going through the polythene, measured by %.
• For temperate climates, a rate of higher than 85% is the target.

Thermal Efficiency

• Where the heat in the tunnel is retained during the night.
• This is measured by thermal retention + thermal transmission = 100 and is expressed as %.
• The higher the thermal efficiency, the better the polythene retains heat.
• The higher the thermal transmission the more energy is lost.

Anti-Drip

• The anti-drip coating reduces condensation droplets and produces more of a film of water.

Benefits of Anti-Drip

• Reduces the risk of droplets then dripping which can cause fungal diseases.
• Improves the quality of light for photosynthesis, Droplets of water cause light refraction reducing the quality of light.

Note: requires adequate management of the internal micro-climate through ventilation.

Lumisol Clear - Clear Polythene

The clear polythene improves the passage of light into the tunnel to promote photosynthesis.
Clear polythene is measured by haze. The lower the % the clearer the polythene appears and the more light is allowed to be transmitted.

• Our clear polythene has 30-35% haze.
• Our clear polythene has 88-92% light transmission.
• Our clear polythene has 80-85% thermic effect.

Benefits of clear polythene:

Improves the quantity of light to encourage photosynthesis.
Encourages early crop yields and crop strength.
Increases daytime temperatures.
5-year incremental guarantee, although a 12-14 year lifespan is not uncommon.

Lumisol Diffused - Diffused Polythene

The diffusion effect ensures better light distribution inside the polytunnel, Diffused Polythene is measured by haze.
The higher the % the cloudier the film is, the more light it defuses.

• Our diffused polythene has 90-93% haze.
• Our diffused polythene has 87-91% light transmission.
• Our diffused polythene has 80-85% thermic effect.

Benefits of diffused polythene:

Reduces the stressful effect of direct sunlight on the plants.
Reduces the risk of leaf burn and crop deformation.
Encourages a more uniform ripening and colouring of the fruit as less shadowing is cast.
Note: designed for use in very luminescent areas of the UK.
5-year incremental guarantee, although a 12-14 year lifespan is not uncommon.

Drip-Line: The Most Water-Efficient Method Of Soil Irrigation

The need for water conservation makes a Drip-Line kit the ideal low-level watering system which places the water where it is required, on the roots, not the foliage/flowers or soaking the pathway.It also saves time, money and effort.

Supplied with all the necessary fittings, drippers, and a hose connector. The kits are supplied with plenty of pipe and fittings for both sides of the polytunnel.

Ideal for both polytunnels and raised beds.

The kit comes with a 16mm OD (1/2” ID) commercial dripline, with pressure compensating emitters positioned every 30cm (12”) along the pipe to ensure even irrigation over three runs per side. Supplied with plain 16mm OD black header pipe for the manifold. Hose connector and all fittings included.

Overhead Sprinkler: For A Blanket Coverage

A little less water-efficient than dripline, Overhead Sprinkler kits imitate rainfall, gently watering the whole area, ensuring blanket coverage inside your polytunnel tunnel.

The Overhead Sprinkler Kit is fastened to the central ridge of your polytunnel with individual sprinklers suspended on 30cm drop tubes. Although its popularity has declined in recent years, it’s still the preferred system for a lot of growers.

The kits are supplied with commercial sprinklers, all the necessary fittings and a hose connector. This central, single spray line is suitable for polytunnels up to 16ft wide. Can be operated with a water timer.

Self-Adhesive Guttering: Harvest Rainwater For Future Use

Harvesting rainwater takes advantage of a clean and free source of water.

Socially acceptable and environmentally responsible, it promotes self-sufficiency and helps conserve resources, and unchlorinated rainwater is better for cultivated plants and crops.

Our simple self-adhesive gutter strips can be easily fitted to new/existing tunnels to provide an excellent method of water collection.