FAQs about Polytunnels

Andy & Kate talk about everything related to polytunnel growing.

They talk about choosing a type of polytunnel, where to put it and share their top polytunnel growing tips!

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A polytunnel is an elongated semi-circular or square shaped tunnel. It is most often constructed using steel and is covered in polythene. Polytunnels come in a range of sizes and are used to keep plants, vegetables and fruits warm enough to grow in temperate regions. It can also enable you to grow fruits, vegetables, and plants out of season.

Within the polythene tunnel, the temperature and humidity are higher. Crops and plants are also covered which means they are not exposed to heat, cold, rain, wind and strong sunlight therefore, they will continue to flourish even during adverse weather conditions. There are many benefits to owning a polytunnel but one is the fact that as a semi-permanent structure, they can be moved if necessary to another location in your garden, unlike a greenhouse.

Growing herbs, fruits and vegetable crops has never been easier with a polytunnel - Learn more about polytunnels.


For years, the gardener has chosen the greenhouse as the tool of choice for sheltering tender seedlings and plants but more and more of us are turning to polytunnels. What do they offer the gardener?

The polytunnel allows many more benefits other than a perfect growing environment;

•    More for your money – for the same price as a small greenhouse, you can have a much larger polytunnel and that means more growing space!

•    Great insulation properties – opting for a thicker polythene means better insulation properties and that means a longer growing season.

•    Easily extendable – plan on a bigger polytunnel in the future? Not a problem because your current polytunnel can be easily extended.

•    Manage temperatures easily too – you want warmth in the tunnel but too much heat can kill off plants and seedlings. With double doors either end, the temperature is easily controlled as are pests and other problems such as fungal spores.

•    Protection no matter what the weather – from gales to autumn rains, to days of endless heat and sun, you control the polytunnel climate and that means success no matter what the weather.

Commercial food growers have long realised the benefit of Commercial Polytunnels and with polytunnels of all shapes and sizes, the domestic gardener can enjoy the same great benefits with Domestic Polytunnels.

What orientation is best?

If you are lucky and have a choice, and you are prone to heavy winds, then we would advise positioning the polytunnel where it will have the most protection, ie next to a wall, hedge, tree-line, etc. If this isn't possible it is advisable to position the length of the polytunnel into the prevailing wind. From a growing perspective it is generally accepted that a North to South orientation will generate slightly lower temperatures than East to West where the sun tracks across the long side of the polytunnel.


A polytunnel is used to extend the growing season for your crops, allowing for a bigger, often higher quality, harvest each year. They help to keep a consistent growing temperature and atmosphere that allows crops to thrive much better than they might do when exposed to the elements. Because the crops are under cover, they are also safe from the mouths of birds and other wildlife.

People also build polytunnels for alternative uses, such as housing animals, covering ponds, and sheltering machinery.

Do they blow away?

This is probably the biggest concern for people who have never owned a polytunnel before. Most people tend to think of a polytunnel as a glorified tent, ready to blow away at the first sign of a breeze. Commercial growers could not afford to have their polytunnels damaged by extreme weather and to this end polytunnels have proved their critics wrong in withstanding the most extreme of weather conditions. Whilst a 100% guarantee cannot be given, if the construction instructions are correctly followed and the structure regular serviced, weather damage is unlikely to occur. For those very exposed sites, we would recommend purchasing base rails (this helps achieve a tight cover), crop bars and triple ridge To view one of our polytunnels withstanding an Atlantic storm with 60mph+ winds, see the video to the right.

Here is another short video of the very same Polytunnel still battling against the elements 2 and a half years later complete with the same polythene cover, no problems so far! Standing up better than the piano.

Here is another short video showing how strong our Polytunnels are under snow.

What can I grow in my Polytunnel?

Anything and everything. Today the polytunnel is used to protect 80% of soft fruit (tomatoes, strawberries, raspberries & blackberries) sold through supermarkets. You probably have eaten a fruit that has been grown under polythene. Polytunnels also protect onions, potatoes, peppers, cucumbers, melons, lettuce, beans, pumpkins and flowers. The list is endless.

Prior to the introduction of Polytunnels in England only 50% of soft fruit was Grade 1, now it is nearer to 90% - For today's commercial growers this represents the difference between having a business and going out of business.

Over the years all types of plants (flowers & vegetables) have been grown with outstanding results, a large percentage of championship plants have been grown under polythene. The growing season is greatly extended by the protection they offer and many new comers are caught out by the rapid plant growth early in the year.

Polytunnel or Greenhouse?

One of the major advantages of a polytunnel is cost. The cost of a greenhouse and polytunnel will vary greatly, depending on the type, design and size of model that is required. Generally, based on like-for-like square footage, the set-up costs for a poly tunnel will always prove the cheaper option.

Polytunnels are not only cost effective when purchasing, they are also easy to construct and have no need for a prepared base It is also generally accepted that building a polytunnel is easier than building a greenhouse, over 95% of polytunnel owners build their own, whereas with a conventional glasshouse only 40% elect to build it themselves. Your workload is reduced. Crops grow faster and stronger. Yields are higher and all for a fraction of the cost of a conventional glasshouse.

Still not sure whether you’d rather opt for a greenhouse or polytunnel? Then take a look at this Garden Answers article Polytunnel or Greenhouse?

Are Polytunnel Organic?

The vast majority of people would argue that the environmental benefits of using a polytunnel hugely outweigh the environmental costs of its production. Using a polytunnel will significantly reduce the quantity of fruit and vegetable you need to buy, avoiding the associated food miles, energy costs and packaging.

All the timber we use is sourced from the UK from sustainable forests and has the FSC accreditation. A polytunnel cover should last for around 7 years, which makes it a fairly small part of the plastic consumption of a "Westerner". The cover can be recycled and be made into smaller covers for cloches and cold frames and a host of other applications around the garden.

The enclosed nature of polytunnels also reduces the need for pesticide and chemical control. A Polytunnel provides an environment that is a natural way to protect plants from disease and the UK weather.

Many champions of the "Organic" and "Self Sufficiency" movement own Polytunnels. Buy that polytunnel, enjoy all the extra food it lets you produce - and start totting up the environmental savings.

What type of doors are available?

Your first big decision when choosing a Polytunnel is almost always..."What size is ideal?". But with First Tunnels theres another important factor to take into consideration..."which doors do I want?".

First Tunnels provides a hinged door for each end... as standard. This means optimum ease of access and extra versatility when it comes to controlling ventilation. So its doubly important you make the perfect choice...

In addition to hinged doors First Tunnel also offer sliding doors. So...what are the benefits of Sliding Doors? - Proper ventilation of your polytunnel is an absolute must during the summer months. And we’ve made it really easy by introducing our fantastic sliding doors as an option on any of our polytunnels. They’re space saving…giving you more room to grow. They don’t blow in the wind. And our ground bolt system lets you control the exact amount of airflow you need. Perfect!

All timber used in our doors and frames are constructed from impressively heavy grades of timber for outstanding rigidity and performance. And because they're so solid, we've even bevelled the edges to make them user-friendly too.

We also understand that some customers have access to a supply of timber or may prefer to design their own size and type of door. If this is the case then you also have the option of excluding the timber door frame and doors and receive a discount.

Do I need to treat the Timber Doors and Frames?

All of our Polytunnels are supplied with doors at both ends of your polytunnel. All the timber used for our doors and for base/side rails has been impregnated with TANALITH-E wood preservative under controlled conditions in a vacuum pressure impregnation plant. Following impregnation the preservative bonds with the wood structure making it impossible to remove. The timber is then protected against fungal (rot) and insect attack to ensure long service life.

How much does a replacement cover cost?

If your polythene cover has past its prime, you have inherited a polytunnel frame or maybe bought a second hand structure, a replacement cover will soon get your polytunnel back in business. Working out how much polythene you will need is simple with the easy to use calculator on our website. Just tap in the length and height of your polytunnel, plus the distance over the hoop and the smart online calculator will work out the rest - in feet or metres. On average, a replacement polythene cover for a 10ft x 15ft polytunnel would cost in the region of £99, cut to fit your polytunnel with no waste and no cutting charge.

What is Anti Hot Spot Tape?

Anti Hot Spot Tape is a self adhesive foam tape which acts as a cushion between the polythene cover and the metal framework of your Polytunnel which can become very hot. (Imagine your car bonnet on a hot sunny day, sometimes it can be too hot to touch) Not only will anti hot spot tape prevent “hot spots” occurring and causing heat damage to your polythene, the slippery surface of the tape allows the polythene to glide effortlessly over the framework preventing abrasion when covering and prolonging the life of the polythene sheet by at least a year. First Tunnels strongly recommend this product.

What happens if I tear the Polythene?

Don't worry, we have a solution. Polythene Repair Tape is a flexible long lasting translucent tape designed to effectively repair accidental damage or tears in polythene covers on polytunnels. Repair tape is available in three widths to suit most applications and is hardly noticeable when applied. Not only is it excellent for repairing polythene covers or cloches, it is the ideal solution for repairing cracked panes in greenhouses. Never the less, it's always handy to have a roll of repair tape on standby for those unforeseen emergencies.

Can Polytunnels be moved or extended?

The climate of 'make do and mend' has led many gardeners to wise up to the fact that IT IS possible to extend, refurbish, or even relocate polytunnels in a bid to maximise growing space. Whether you are modifying or extending an existing Polytunnel, we would suggest this is best done when your cover needs replacing as it is not recommended that the polythene is reused. If you are looking for new foundation tubes, crop bars or even ridge tubes, the additional help of the replacement tube design service on First Tunnels website, allows gardeners to quickly and easily design a tube that is perfect for their polytunnel.

What are all the different Polythene Covers and how long do they last?

With First Tunnels offering different types of covers you can achieve whichever type of environment suits your needs. Super White polythene offers a cooler environment for shade loving plants/shrubs or animal shelters. A Super Therm cover is also available which retains more heat. There is even the option of covering your Polytunnel in Net.

We have a number of polythene types. All First Tunnels polythene used is up to 800 gauge (200 micron) - that's the thickness used on Commercial polytunnels. Our most popular cover is the Super Therm and is supplied with a guarantee for 7 years, but it has been known for a cover to last 10 years. Other specialist types of film are also available and are guaranteed for 5 years. When comparing specifications with our competitors ensure you check that they are supplying a 800 gauge polythene cover and ask what the guarantee is....

Can Polytunnels be heated?

Yes. The polythene is designed to withstand both hot and cold environments. See our range of Heaters. If you wish to consider heating a polytunnel then why not consider using a mini polytunnel to protect tender plants inside your already existing polytunnel, like "double glazing". This method saves on your heating costs. If you want to discover more about mini polytunnels then click here.

What are the planning regulations for Polytunnels?

In general you do not need planning permission for sheds, greenhouses, summerhouses or polytunnels. You can't build over 3m high (or more than 4m if it has a pitched roof). A pitched roof has its ridge at the centre, and both sides slope down at the same angle - this accurately describes a polytunnel roof.

Take extra care if your site has a listed building or resides in a conservation area, national park, or area of outstanding natural beauty. There are further restrictions to planning in these cases. To access an interactive planning tool to check on the current guidelines, click here.

If you are thinking of ordering a large commercial sized structure or more than one or you have any worries at all, have a word with your local planning department. Please click here to download a planning guide for farmers.

Should you need planning permission, we can provide CAD scale elevation drawings. Please click here for an example. There will be a small charge for this service, which would be credited back should you decide to order the polytunnel once planning permission has been granted. Please contact us to discuss.


This is a really simple reward system for those people who buy our polytunnels online. Our store calculator will automatically advise you about the great BONUS SAVES that are available. For example, when your order has qualified for a discount we’ll highlight the saving before you checkout. Should your order be falling just short of a BONUS SAVE! we’ll let you know, giving you the opportunity to purchase the really useful smaller items and accessories that will give you a BIGGER SAVING.

We always aim to offer our customers good value for money, and because our offers are generous, short term deals we cannot always offer a BONUS SAVE as well as a promotion or timed offer.


If it is maintained and constructed with quality materials, a polytunnel can last between 15 – 20 years before the frame, or at least parts of the frame, need replacing. The polythene sheet of a polytunnel will need to be replaced every 7 – 10 years.

Read More: How long does a polythene cover for a polytunnel last?

How can I Harvest Rainwater from a Polytunnel?

As we have been asked this question on numerous occasions, we thought it would be a good idea to demonstrate our own solution. Rather than use adhesive stick on guttering which can prove expensive and unreliable, check out this innovative way of collecting rainwater from a Polytunnel, providing off - mains supply for remote areas or allotments. Please bear in mind First Tunnels recommend the installation of a side rail at approximately 3 foot high to accommodate this system, this way you can securely batten the guttering and downpipe along the length of the structure providing an excellent robust fit.

Does rain stop play?

Not exactly a frequently asked question but this short film highlights a major benefit of owning a polytunnel. Not only do your crops and flowers grow faster and stronger when sheltered by winds, frost and the battering of rain, a Polytunnel certainly gives you the gift of gardening outdoors, indoors. When the rain is pouring down, there are few better places to hide and get on with some digging. Especially when the allotment site is empty!

Good for your health...and wealth

Sounds too good to be true...well here's some food for thought.

Grow more...for less
Growing your own can mean big, big savings on the cost of buying your favourite fruit and veg from the supermarket or the greengrocer. Even better, the microclimate in your polytunnel means even bigger, healthier crops...and a much, much longer growing season. And the more you grow...the more you save!

Miles of smiles
With fuel prices at an all-time high, cutting out trips to buy your fruit and veg will mean less miles racked up visiting the forecourt too. That's money in the bank...straight away. And while you're saving £££'s, you're helping save the environment too. Bit of a win win!

Exercise everything...except your wallet
Throwing your heart and soul into things inside the polytunnel is a good workout and a lot less tedious - and costly - than paying to go to the gym! And for anyone who has problems bending down, raised beds bring the gardening up to you, so tending crops and weed management is much, much easier.

Something you can't put a price on...
Your inner health! You control what - and how - you grow. So the pesticides, herbicides and other nasties that might have been used on commercially grown crops are kept out of your polytunnel...and out of your body. And don't underestimate the value to your wellbeing that comes from the simple joy of seeing your hard work bearing fruit.

Do You Still Have Questions?

Our team are on hand to answer any questions you may have.

Contact Us ›

We are more than happy to assist or provide further information relating to our polytunnels. You can contact us by email or telephone our office on 01282 601253. You could even become a First Tunnels Facebook Friend and share your gardening construction tips, growing advice, swap recipes, enter competitions and enjoy other fun things.