Polytunnels work by using the material of the polythene cover to heat up the interior of the tunnel from the sun. Humidity and hot air created by the sun are retained within the polytunnel structure to create a microclimate that allows plants to grow inside your polytunnel. Vents are used to control the temperature and humidity inside the tunnel. Polytunnels are especially useful for prolonging the growing season for vegetable gardeners. Our guide covers the best polytunnels, polytunnel kits, how polytunnels compare to greenhouses and the main things you need to do to care for your polytunnel.
THIS POST MAY CONTAIN COMPENSATED AND AFFILIATE LINKS. MORE INFORMATION IN OUR DISCLAIMER
What is a Polytunnel?
A polytunnel is a frame that is covered in polythene of various types to create an internal microclimate in which to grow seedlings and plants. The ability of polytunnels to create these microclimates means that you can extend the growing season for native fruits and vegetables and also grow fruit and veg that wouldn’t grow naturally in the UK. POlytunnels are used to protect from the worst of the weather – cold, strong wind and snow for instance. Polytunnels are similar in many ways to greenhouses, but there are also differences between greenhouses and polytunnels.
The polytunnels we’ve selected are easily installed without expert help, you’ll just need a few tools. They’re also designed to fit into a regular garden or on an allotment, no need for acres of space! And we’ve also looked at an extra-wide one, for much more space, as well as a mini polytunnel which you can use to bring on seedlings and small plants.
Best Polytunnel Kits At a Glance
|Details of Polytunnel Kits||Highlights||What It Looks Like||Read Reviews & Buy Now!|
|Birchtree - Best Polytunnel Kit||• Variety of sizes from 2.5 metres long to 6 metres long|
• 6 sectioned frame on the 6-metre long version
• 2 metres high, 3 metres wide
• Super strong 25mm galvanized anti-rust 0.8mm thick steel frame
• 140g transparent PE material with green checkers is UV protected for longer life.
• 2 double zipped doors with metal zip heads
• Each section has a window flap for further ventilation.
|Read more reviews and buy now|
|Outsunny Large Polytunnel Kit||• Available in 3.5-metre length and 4.5-metre length.|
• Zippered roll-up door
• 6 roll-up mesh windows to allow ventilation, but not bugs and pests.
• UV resistant PE cover
• Rust-resistant galvanised steel frame
• 4 wind ropes
• 4 extra slant supporting rods for the roof
|Buy this large polytunnel kit now|
|Outsunny 2.5 x 2 x 2 m Large Galvanized Steel Frame Outdoor Poly Tunnel||• 2.5-metre long polytunnel|
• Galvanised metal poles with connecting screws for strength
• 4 pull ropes and ground nails for fixing
• Ventilated, Anti-UV PE cover in white
• Polyethene cover has grid threading for strength
• Large double zipped door
|Read reviews - the best small polytunnel kit|
|Haxnicks Easy Seedling Tunnels - Mini Polytunnels||• 3 tunnels per pack at 80cm each|
• 18cm wide and 12cm tall
• Galvanised steel hoops that peg directly into the ground
• Covers are made from tough U.V. stabilised polythene
|Read reviews and buy mini polytunnels|
Why Use Polytunnels?
Polytunnels allow you to extend the growing season of the fruits and vegetables that you want to grow. Polytunnels will let you grow vegetables and fruits not normally grown in your environment. They are great for starting seedlings and young plants early in the growing season and protecting them from the weather. Polytunnels are generally cheaper than greenhouses, and usually larger too. Polytunnels allow you to create a stable microclimate in which you can grow vegetables and not have to worry too much about the vagaries of the weather.
What’s the difference between Polytunnels and Greenhouses
Greenhouses and polytunnels work similarly to each other – they lengthen the growing season, create a growing season for some fruits and vegetables and protect your plants from both the weather and animals, bugs and birds.
Polytunnels tend to be cheaper to buy than greenhouses. Polytunnels tend to be quick to put up and can be built straight onto a soil base. Unless you go for a mini greenhouse (see our guide here) greenhouses tend to need hard and level standing to be based on. You can easily store and move polytunnels around the garden or allotment and the steel frame tends to last for years.
Aside from mini-greenhouses, regular greenhouses tend to be much more expensive and more difficult and time-consuming to put up. They tend to be heavy as they’re usually made from polycarbonate plastic or glass. Greenhouses do tend to last a lot longer than polytunnels, however.
Reviews of Best Polytunnel Kits
The main difference between polytunnel kits is the size of the polytunnel and the type of polythene that the cover is made from – here are our reviews of the best polytunnel kits, materials and what’s available in the UK.
Best Polytunnel Kit – UK Market – Birchtree Foxhunter – 6 METRE Polytunnel
The amazing polytunnel kit gets really high reviews (and there are a LOT of them! – so it is not just us that think its fabulous. It comes in various sizes, and that’s why we’ve gone for this as the best polytunnel kit and in this review, we’re looking at the 6-metre long polytunnel option. The polytunnel frame is made of super-strong 25mm galvanized anti-rust 0.8mm thick steel and the transparent PE material that makes up the cover is UV protected and 140g weight. Buy this best buy polytunnel kit now
Key Features of the Birchtree Polytunnel Kit
- Variety of sizes from 2.5 metres long to 6 metres long
- 6 sectioned frame on the 6-metre long version
- 2 metres high, 3 metres wide
- Super strong 25mm galvanized anti-rust 0.8mm thick steel frame
- 140g transparent PE material with green checkers is UV protected for longer life.
- 2 double zipped doors with metal zip heads
- Each section has a window flap for further ventilation.
Best LARGE Polytunnel Kit – UK Market – Outsunny Galvanised Polytunnel
Available in both 3.5-metre length and 4.5-metre length this galvanized steel polytunnel with a white polytunnel cover is a great way to extend your growing season. There are 6 mesh windows with roll-up flaps for ventilation. The PE cover is fully closeable and waterproof plus its UV resistant, allowing sunlight to pass through while maintaining higher humidity inside. The galvanised steel frame is resistant to corrosion, chipping, peeling and rust and comes with win ropes and 4 extra slant rod supports for the roof. Buy this fabulous large sized polytunnel kit now
Key Features of the Outsunny Galvanised Large Polytunnel Kit
- Available in 3.5-metre length and 4.5-metre length.
- Zippered roll-up door
- 6 roll-up mesh windows to allow ventilation, but not bugs and pests.
- UV resistant PE cover
- Rust-resistant galvanised steel frame
- 4 wind ropes
- 4 extra slant supporting rods for the roof
Best SMALL Polytunnel Kit – UK Market – Outsunny 2.5 metre Polytunnel
If you’re in the market for a small polytunnel, this 2.5-metre long polytunnel from Outsunny is a great option. It has a durable polyethene covering with grid threading and a sturdy galvanized metal frame for long-lasting use. The PE cover is ventilated, anti-UV and age-resistant. There are 4 ventilation windows and a large double zipped door. The frame is connected with screws between metal poles. Buy this fabulous small polytunnel kit now.
Key Features of the Outsunny 2.5-metre longPolytunnel Kit
- 2.5-metre long polytunnel
- Galvanised metal poles with connecting screws for strength
- 4 pull ropes and ground nails for fixing
- Ventilated, Anti-UV PE cover in white
- Polyethene cover has grid threading for strength
- Large double zipped door
Best MINI Polytunnel Kit – UK Market –Haxnicks Seedling Tunnels
If your need is a LOT smaller, then these mini polytunnels are quite simply fabulous. They’re perfect for creating a moist microclimate for the germination of seeds and for their rapid growth. They’ll lock in moisture and protect from weather and pests. They’ll even warm the soil or compost ready for sowing seeds. They have galvanised rust-resistant steel hoops which peg directly into the ground to keep the tunnel in place and they can be stored really easily. There are three in a pack and each is 80cm long, they’re 18cm wide and 12 cm tall.
Key Features of the Haxnicks Mini Polytunnel Kit
- 3 tunnels per pack at 80cm each
- 18cm wide and 12cm tall
- Galvanised steel hoops that peg directly into the ground
- Covers are made from tough U.V. stabilised polythene
Polytunnel Kit Buying Guide
Here’s just a few of the features and elements that you’ll need to consider when looking at buying a polytunnel.
What to Consider when Buying a Polytunnel
You’ll want to look at a few key elements when you’re looking at buying a polytunnel, here are key features to consider.
- What space do you have available? Will the polytunnel that you’ve chosen fit that space?
- What do you want your polytunnel for? Will the size of polytunnel that you’ve chosen meet those needs? Try to plan for 5 years.
- Can you build the polytunnel yourself? All of the kits that we’ve selected in this guide are designed to be built by the home garden user.
- Are the materials high quality and durable? Check the reviews of your chosen polytunnel. Each of the polytunnels we’ve reviewed receives positive reviews on built quality and material quality.
- Accidents happen – make sure that you buy a standard-sized polytunnel so that you can buy a replacement cover when you need one.
Size of Polytunnel
Look at what space you have available. Look at what you want to grow inside your polytunnel and whether you’ll be able to fit it all in.
Polytunnel Frame Materials
While the frames of mini-greenhouses tend to be made of aluminium you’ll want to look at polytunnels that are made of galvanized rustproof steel. It’s lightweight, will last up to 20 years and most importantly it’s rustproof!
Polytunnel Cover Materials
Polytunnel covers are made of polythene. You’ll usually have the choice of green or white. You’ll want to AVOID clear covers. Green and white polytunnel covers include UV protection and therefore last longer, they will also protect your vegetables and plants in summer from sunburn.
FAQs on Using Polytunnels and Buying Polytunnels
Got questions about using polytunnels? Or want to know what to look for in a polytunnel and we haven’t answered your questions? Check out our frequently asked questions about polytunnel kits below, or ask us yours in the comments.
Which is best a polytunnel or greenhouse?
A polytunnel is likely to cost you less than a greenhouse unless you’re going for a mini greenhouse. Greenhouses tend to be heavier, need to be built on flat, solid ground, whereas Polytunnels tend to be built directly onto the soil. It depends on the budget you have and what it is you’re looking to do. We love mini-greenhouses for the backyard and a polytunnel for the garden, where we have more space and want to grow more veggies.
What size polytunnel should you go for?
The size of the polytunnel you buy will depend on the space you have available. We’d always go for the biggest one you can, as it gives the most options for your future growing. We’ve included reviews on a variety of sizes and all the manufacturers that we’ve selected have a variety of sizes available. The most popular size of polytunnel kit is 4 metres long x 3 metres wide x 2 metres high.
What material is best for polytunnel frames?
Most polytunnel frames are made of galvanized rustproof steel. This lightweight material is long-lasting – most frames will last up to 20 years. It’s easy to put together, and to store and doesn’t rust.
Where should you place your polytunnel?
Usually, the answer to this is “where you have space”. If you, however, have the choice, then you’ll want to run the long side from north to south. This will maximize your growing experience and make sure that you avoid the excessive heat likely if you’re running it from east to west (the sun will go along the length of the tunnel).
What maintenance does a polytunnel need?
The best time for maintenance of your polytunnel is autumn and winter. Clean the cover thoroughly inside and out. It’s important to have at least an annual clean of your polytunnel to ensure that you remove any disease vectors and bugs to prepare your polytunnel for spring planting.
What’s the best position for a polytunnel?
If you’re in the lucky position to be able to have a choice where you site your polytunnel, then the best position for a polytunnel is to have the long side running from south to north. This gives you the ability to avoid the high heats of summer. If you have to site it east to west then you’ll be facing on to the midday sun, in the heat of summer, this is not ideal. It will also mean that if your summer crops grow tall, then they could shade some crops in the north bed.
Are polytunnels worth it?
We think so. We think they’re a small investment for a lot of extra growing capability. It’s also a heck of a lot more motivating when the rain (or snow) is coming down or the wind is howling to get out there and start doing some work inside the tunnel rather than outside in the elements!
How long does a Polytunnel last?
Polytunnels are made up of two elements – the frame and the polythene cover. The frame should be steel (and possibly coasted) and a polytunnel frame should last for 20 years or more. A polytunnel polythene cover should last between 5 and 10 years. Better quality definitely lasts longer, but there are other considerations with the cover too. UV degradation is caused by sunlight and can impact the length of time that a polytunnel cover can last. Wind, rain and other bad weather can also impact how long the covers last too. Be sure to make repairs as soon as accidents happen to ensure your polytunnel lasts longer.
Can you grow in a Polytunnel all year round?
Yes, you can grow vegetables in a polytunnel all year round. You’ll need to check on the growing requirements of specific vegetables but the whole purpose of the polytunnel is to increase your growing season.
Do Polytunnels need ventilation?
Yes. POlytunnels need ventilation in the summer, this is the main way in which you will cool your polytunnel in the summer. You’ll also need to ensure that decent ventilation will help prevent crop disease as well.
Why are Polytunnels green?
Some polytunnels have a green cover, some have a white cover. With most polytunnel kits you can elect for a white or a green cover. Green polytunnel covers let less light permeate through to the vegetables, so they may be better in some environments – i.e. in high sun areas. Most green polytunnel covers have a mesh within the polythene which increases the strength of the cover making it last longer. The green will also stop your plants from getting burnt with the sun in the heat of the summer.
All our guides to the best garden equipment
- The best gardening gloves in the UK
- The best garden kneelers in the UK
- The best food dehydrators in the UK
- The best potato grow bags in the UK
- The best vegetable gardening books in the UK
- The best grow your own herbs kits in the UK
- The best expandable hoses in the UK
- The best compost bins in the UK
- The best mini-greenhouses in the UK
Final Words on the Best Polytunnel Kits
If you’re serious about growing your own food then investing in a polytunnel is something that you won’t regret. They’re no a huge expense, but they can extend your growing season significantly and even open up growing some fruit and veg that you might not necessarily be able to grow in the UK. These polytunnel kits make it seriously easy to both buy everything that you need, install and get started growing in polytunnels. Let us know what you decide to do and which you’ve found to be the best polytunnel kits for your veggie growing needs.LetsGrowCook is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com, amazon.co.uk, amazon.ca. Amazon and the Amazon logo are trademarks of Amazon.com, Inc. or its affiliates..