Polytunnels, advice on buying

Some tips to help you make a good choice

Polytunnels are wonderful structures and good value compared to greenhouses. Once erected they will be there for several years, so check out my tips before buying.

I have used polytunnels since 1983 when I bought 3 of 18×55 feet (5.5x17m) and they served me well except that their 1in/2.5cm tubes were too thin for my exposed site. In a gale of March 1988, one of them collapsed after the wind ripped out its polythene on the far side, see below for how that works.

How big?

I would buy the largest you can fit into your area, because the space is useful for storage and drying washing as well as for growing! One always finds more to plant in a tunnel. Hoops are 5 to 6 feet (1.5-1.8m) apart so length is multiples of that. I reckon that 20-30 feet is a good length for even ventilation, whereas tunnels of say 60 feet length can have pockets of ‘dead’ unventilated air in the middle.

My current tunnel is 42ft long, and works especially well for winter salads, without any supplementary heat.

Winter salads in no dig polytunnel in December
Winter salad plants 19th December 2019, before a pick for Christmas. They carry on producing new leaves until spring, from transplanting in October.


  • North to south is ideal so that tall crops in summer cause equal amounts of shade to either side, also to reduce overheating in summer.
  • An east-west structure is face on to the midday sun and in a hot climate this is not ideal during summer. It also means some shading of crops in the north bed when summer crops grow tall in the middle.

However any orientation is possible and I have tried many, with success. Other important factors to consider are aligning a tunnel up-and-down any slope (beds across slope are harder to water and mulch), and having the doors at convenient points for access and watering


Plants like fresh air and its important they have enough, rather than striving for maximum heat. Air in a polytunnel circulates from one end to the other, and if possible I recommend leaving a gap between the top of doors and the frame above them, say 6in (15cm), so that a small amount of air can always flow through and increase carbon dioxide levels, without a draught at ground level. I find that winter salads stay healthy, without mildew problems, yet without any need to open and close doors for much of the winter. One job saved!

The option of side vents (instead of the polythene going to ground level) is in my opinion not necessary or suitable for vegetables in temperate climates such as here. Side vents reduce temperature in windy weather, while doors at both ends offer enough possibility to admit fresh air. Its cheaper and simpler to cover the hoops with polythene only, to ground level and below. Keep side vents for long tunnels only, above a length of 40-50 feet (13-16m).

Polythene attached at ground level, or buried?

I recommend burying the polythene all around in trenches of one spade’s depth, in order to have a polythene barrier in the ground. This protects against

  • pests entering, such as rabbits, slugs, cats and dogs
  • weeds creeping in, including couch grass, buttercup, bindweed
  • too much draught and cold air around plants’ leaves.
Filling a trench for new polythene at Homeacres, January 2013
Filling a trench for new polythene at Homeacres, January 2013

It is sometimes claimed to be easier and quicker to attach polythene at ground level to battens or rails. However this means you need to dig holes for the foundation tubes, rather than simply knocking them in. Also for windy sites, you may need some concrete in there. All the fixings you need involve extra expense, and are mainly worthwhile if there is simply no room to dig a trench.

My First Tunnels polytunnel has base rails, professionally installed, and they are working well. I asked the fitters to leave a polythene skirt below the base rail (see photo below), which we then dug into the soil.

Foundation tubes

When burying polythene in a trench, tubes simply need to be hammered into the ground about 12-18in (30-45cm), where their role is to give the structure some rigidity, that is all. When polythene is bured, the tubes are not anchoring the structure in place, but keeping it steady in wind.

In contrast to this, when polythene is attached to a rail and not buried, the foundation tubes have more importance as they are what holds the structure in the ground (rather than the buried polythene) and so you need more expensive tubes with metal brackets on their ends, and each one requires a dug hole, sometimes with concrete.

Crop support bars

Although an “extra” I would always buy these, so you have support for climbing plants from tomatoes and cucumbers to beans and melons. They span across from side to side at about or just over 6ft (2m) high, so you can walk underneath, yet also reach to tie strings or stakes.

How many years before re-cladding?

Polythene needs replacing every 5-8 years, depending how windy your site is and how tight you can stretch it. Polythene is easier to make tight when the cover is put on in warm sunshine, if possible. I have often done it in January and managed alright, but the skin is definitely slacker and more prone to damage than when clad in warm sunshine.

The First Tunnels fitters have achieved a tight finish on my 2019 tunnel, erected in May warmth. They reckon the polythene can last for 15 years! This tunnel is 12ft longer than my first one, same width, and has lovely straight sides.

New polytunnel First Tunnels
23rd May 2019 after two First Tunnels fitters had started at 11am the previous day, 18x42ft with lovely straight sides, and a polythene skirt from the base rails

What kind of polythene?

More types become available and choosing is then difficult. From tunnels I have seen with the more expensive thermic or anti-condensation polythene, I doubt that their extra cost is worthwhile. I recommend the standard, light-diffusing polythene which admits around 89% of daylight. Always use horticultural grade polythene, which has a uv stabiliser, without which it would be brittle and break within a year.

A friend recently noticed the great clarity of my standard, light diffusing polythene which is now 3 years old. I had recently washed it with a wet sheet and brush to remove lichen and moss.


You use these a lot so suffice to say, they are worth spending money on to have the ones you like. Home-made is certainly possible, note my tips on ventilation. Its the area where you can be most creative, especially if you enjoy carpentry. For door frames, 4×2 timbers are good.


I like hand watering, but it needs more time. I have two spray lines supplied by First Tunnels, and do not use them a lot because the distribution is uneven. There are several dry zones where we need to water by hand afterwards.


For information on polytunnel growing, have a look at my ‘Polytunnel and Greenhouse Growing‘ YouTube playlist.

157 thoughts on “Polytunnels, advice on buying

  1. HI Charles, thanks for all the advice – I went with First Tunnels, and put down ground cover inside it thinking it would be even better than cardboard. I’ve put compost on top and now realise that as the ground cover doesn’t degrade like compost, there will be no chance for worms to come upwards or plants to grow further downwards 🙁 I haven’t planted anything yet – would it be better to remove the ground cover and replace with cardboard before I do?

    1. Hi Catherine, and yes absolutely 100%, remove that cover! It’s exactly as you say, an interference to soil process.
      I hope you enjoy your new tunnel, and I’m sure you will.

  2. Hi Charles
    A really interesting article, thank you. I am looking at First tunnels and you are right, the options are vast and daunting. The space I have will allow for a 3m x 6m tunnel. It is at the bottom of a hill and sheltered from Westerly winds. The latest storms didn’t even move an aluminium brassica cage just pushed in the soil. The ground is soft and I can dig up to half a metre down with no real effort. Given the size, location and ground conditions, do you think that a poly tunnel would be perfectly secure without the need for base plates and base rails then? Just trench it? How easy is it to adjust the tension with a trench, should it become slack?

    1. That sounds very promising Julia.
      One thing about trenching is that you cannot adjust the polythene tension, so I’ve become more in favour of base rails, and advise anchor plates because they are not expensive and will give peace of mind

  3. Hi Charles, Lovely article thank you.I am thinking of building a polytunnel on the west of Ireland a windy site. Hoping to build 4m x 12m . What size tubing should i use for hoops ?

    1. Thanks Patrick and I recommend 2in/5cm tubing. Since I switched to this from 1.5in, the structure is so stable. Helps the plastic to last longer too.

      1. thank you Charles. Do you think that I could be able to get a cheap pipe bender to bend 2in/ 5cm piping. I have looked on American YouTube videos and all I can see is Tunnel Pipe Benders for lighter gauge piping. I am trying to keep the cost down. Thanks again Charles. Kind regards Patrick

        1. I think it’s unlikely Patrick. The point of these popes is their strength. A bender would therefore be expensive.
          Plus the tunnel cost is in all the extras like doors.

  4. Hi Charles,

    Great advice as usual! We are about to erect large polytunnels (Cork, south-west Ireland) and follow your no-dig techniques but at the location, the soil gets quite waterlogged in winter months (rushes love it there). We are thinking of putting in drainage trenches around the tunnels to prevent them getting water logged and to help the surrounding soil. Would you agree that’s a good solution and if so, would you have any guidance on how to approach them – e.g. depth, width and distance from the tunnel sides? Thanks a million, Eliza

    1. Thanks Eliza, nice to hear except for the rushes!
      It sounds like some kind of site drainage will be worthwhile, because you could indeed have swamp like conditions near the poly tunnels otherwise.
      I would lay drains within a metre, but it’s something of a guess because without seeing, it’s hard to say for sure, and good luck!

  5. Hi Charles,
    Love reading your gardening tips and watching your video
    ‘s on ‘You Tube. I have recently located to central Brittany and am keen to grow my own food ,i have a south facing field but the wind blows predominately from the West.I am going to buy a polytunnel of 8m x 5m to start me off.You mentioned that i should site my tunnel in a North/South direction so my produce won’t fry in the summer sun and to keep shadows to a minimum.Would it be ok to site my tunnel at a 45° angle NE/SW so i get air blowing through the gap above my door.Also is there a way to collect water from a polytunnel as i’m on metered water and my house where the water butts are is some way from the field. Thanks!

    1. Hi Andy,
      Thanks and that sounds a nice relocation!
      Yes that could work well because the main consideration is site, and it’s rare that one can have everything perfectly lined up.
      There are ways of attaching guttering to the sides of poly tunnel. I have not done it but you should be able to find information online, for example using a batten on the inside to screw the guttering to, through the plastic

  6. We have just built a Polycrub in our garden and it has been very productive.
    They come from Shetland and can withstand gales and the harshest of climates. An excellent investment and visually very attractive.
    Check out the website – polycrub.co.uk

  7. Hi Charles,
    I have just bought a house with a huge vegetable plot and I am preparing to buy my first polytunnel. The area is sheltered by a hedge and I have an edged bed of 8m x 4.8m which I plan to use for the tunnel. This is approximately 1/4 of the available planting space in total. I am debating between 3x6m or 4x6m. I see you say get the biggest the space will allow. I think that even with the larger size there is still enough space to dig a trench and bury the sides of the plastic sheeting but I am hesitating, maybe a bit intimidated by the size! What amount of space would you recommend leaving around the outside of a polytunnel?
    Thanks for your advice 🙂

    1. Hi Liz
      That sounds exciting. The 4 m width will give you some extra height and volume of air which will be less humid and probably result in less blight and mildew.
      However you don’t want to sight it too close to a hedge, whose roots will be in the soil underneath and using the water you put on your plants.50-60cm free space around edges should be ok.

  8. Thank you for your article, and incredible books and inspiration!
    I’m a domestic gardener with limited physical capacity – since reading your books I’ve installed 3 small resided beds using no dig & they’ve been amazing. I have space to install a tunnel, Max 3x5m. Only issue is I have fruit trees & a few chickens on one side and a massive ash tree on the other. It would get pretty good light but underneath would be roots – I was thinking of filling sacks with compost to grow inside? Sounds silly but I really want somewhere I can be with the plants when the weather is more challenging. Any thoughts or ideas would be much appreciated. Thanks

    1. Hi Richard and I’m happy to hear that you’re succeeding with your gardening. That certainly is one brilliant aspect of any undercover space, but you also can be undercover as well as the plants!
      Your idea about filling sacks with compost is a very good one because they are not permanent, unlike a plastic membrane. And you can refill them as needed.

  9. Hi Charles,

    I live in rural North West Ireland, 1.5 miles from the Atlantic Coast, at the base of a mountain. It can be very very windy and very, very wet.
    I’ve established the best site for my tunnel/s, as it is the highest point among the 5 acres, with reasonable natural drainage and actual soil rather than peat. I would like to plant a permanent garden featuring only edibles including fruit trees, vegetables and perennial shrubs among the annuals, with the focus on edible florals. I will have a combination of direct planting and make raised beds from the many rocks around the place.

    Given the challenging environmental conditions can you suggest the largest size of tunnel you think I could accommodate and any modifications that may be needed (I intend to have it installed professionally).

    As the land is terribly poor and full of rocks, I was considering allowing a couple of pigs and some chickens to let loose in the tunnel before I plant to root about a bit first and fertilise as they go. Is this a good idea or best avoided?

    Thank you for any sage advice.

    1. Hi Laura, and that sounds a challenge! I would go for 14 x 30′ if it fits. I would not let a pig in there but chickens could work. Pigs could easily lie against and stretch the polythene, or break a door.
      Not sure I would use rocks as bed edges because their size means you bend a long way over to reach into your bed.
      I wish you every success and that the weather is not too bad!

  10. Hi Charles,
    I inherited a polytunnel that was squeezed in behind a large double garage and a tree and hedge boundary. I have one huge sycamore within a couple of metres from the tunnel and one metre away from a Laurel and beech border hedge. The first year I dug out the polytunnel ( I wasn’t very experienced then) in spring before planting tomatoes and cucumbers and had a really good crop. The following years following year I did not dig out and my crops were poor.
    This season I decided to leave side no dig and the other dug. I have been out there now and even after leaving a hose on it a considerable time last night the soil is bone dry. So I started to dig and within only a cm or so there is a mass fibrous network of roots forming literally a mat underneath the surface. I don’t use the polytunnel over winter and I am presuming the tree which is huge puts down its fibrous roots and takes all the water and nutrients out of the soil. I do grow toms in bottomless plastic pots filled with fresh compost and I do add a new layer on top each spring, but all that seems to be happening is that the soil surface is getting higher, but it’s like pale dust.
    As I
    A biochemist I have studied tree root networks but I cannot see how no dig is going to work when faced with such fibrous growth from a very established tree.
    My question is should I just clear the polytunnel completely, flag it and resign myself to growing in a raised bed where I can control the soil environment a bit better? It’s also back breaking work digging out the polytunnel each time as the roots are like a carpet. There’s also nowhere else to site the polytunnel so I’m limited. Many thanks Charles

    1. Hi Deborah, and it’s a sure thing that those tree roots are loving your undisturbed soil! Such a pity.

      Unless you want the horrible work of digging that soil, I would indeed grow in containers on top, of whatever kind.

  11. We are loving the greens from our new polytunnel and would recommend the no dig beds too!
    However, as it has been so warm recently, many of our plants are going to seed already. Is this what we should expect and keep succession going, or is there something else we can do?

    1. Hi Alice. It depends what greens you are growing because if they are mustard and salad rocket, for example, they naturally seed in the spring and early summer. Therefore it’s totally normal and check my sowing timeline for other such examples.

  12. Hi Charles,
    This is a great article and has been very enlightening and helped me narrow down some specifics.
    I would however, appreciate some advice. I am currently looking at buying my first poly tunnel and I am swithering between suppliers. I am looking to buy a 14/16 feet by 40ish feet poly tunnel, my dilemma is I live in a fairly windy part of Scotland, not extreme exposure however, it is not uncommon to see trampolines rolling by my window and the occasional shed roof therefore, should I plump for the sturdier more expensive brand or will the other popular brand be up to the task?
    I am also not sure whether to trench or not, I have some cute but pesky thieving wild rabbits around, would this be enough to deter them ? I suspect not however, perhaps you may have another suggestion?

    1. Hi Tina.
      The polythene is thick and will keep rabbits out.
      Base-rails are stronger now and so are anchor plates. If going for baserail, you need to dig in a skirt of polythene.
      I recommend First Tunnels 18ft wide tunnel x30ft or 36ft long. It has 2in diameter hoops which are so sturdy in wind.

  13. What a treasure to find your site! We live in Yorkshire and a 25 year old dream is about to come true – I can finally afford a polytunnel!!! Hoorah!!
    I’m about to buy a 10′ by 30′ one from Northern Polytunnels and have just a couple of questions left!

    Would you recommend clear or diffused polythene? I thought clear would be better as we’re this far north but I’m not sure.
    Secondly, I’m veering against side ventilation and what you’ve said kind of supports that, but I’m worried that a single door at each end might not be enough…?
    Thirdly, as I still work full time (and am quite old and knackered!) I was thinking of investing in an automatic watering system for it. I don’t know if you’d recommend a sprinkler system or a ground level one…I’m planning on having a lot of hanging baskets as well as little fruit trees and veg plots as well – ideally a combination would be good but I don’t know if you can do that….
    Anyhow, thank you for such a great site and for your availability to all we polytunnel newbies!
    Best wishes,

    1. Lovely to read this Fiona and I wish you happiness with it all.
      The diffused polythene is good and allows I think as much light as clear. For ventilation I found that a door either end was enough for my 30 foot, but not for the current 42 foot. But the problem is only in high summer, when the sun is hot, and most of the year you probably are better without side netting.
      Automatic watering sounds great but I find it not so accurate as water in by hand. If you go for overhead, which I refer to the drip lines, I suggest a misting outlet rather than ‘rain’.
      Drip lines do not water all the soil and a result can be diminished soil life because you have dry areas.

  14. Hi Charles,
    Brilliant, thanks for so much really sensible information. Our first polytunnel ( well actually it’s a polycrub, we are in the NE of Scotland) is almost complete. It is standing on very coarse gravel, where the builders had their potacabin. I’m planning 24″ high raised beds, is it still worth putting cardboard at the bottom? I’m hoping to source manure for the base, and will purchase compost and topsoil. Do you think that will be nourishing enough for crops? Thanks, Jane

    1. That sounds exciting, and you have no need for cardboard. Just compost if I were you, which includes old animal manure, any decomposed material.

      I would not use any soil or very little. It’s often poor quality and does not decompose so your beds stay maybe too full

  15. Dear Charles
    Thank you for this very helpful article. I am in the process of putting up a 12ft x 25ft polytunnel and have gone for timber base rails in order to get maximum tension of polythene. I would like to trench the plastic skirt as well in order to provide a barrier against pests weeds and draughts- if this is its sole purpose (not anchoring) how deep do you recommend I need to dig the trench?
    When trenching to anchor the tunnel they suggest starting the trench 10cm away from the poles- would this be advisable in this case also?
    Many thanks indeed.

    1. Hi Jemima. Yes skirt is a weed and pest barrier, not for tensioning. Draughts are not a problem within reason. My trench is only 15cm deep. And 10cm from poles is a good plan for more space inside.

  16. Hi Charles – very helpful article, thanks.
    I’m thinking of getting an 8 foot by 12 foot polytunnel from First Tunnels and I have a couple of questions. You say that the 25mm tubing used on your original tunnels wasn’t strong enough, but I see that’s what First Tunnels supply with their domestic tunnels. I’m thinking that because the hoops are smaller it should be OK, is that right. My London allotment does get a bit of wind but not like an exposed rural location. Secondly, about the doors. First supply mesh covering for the top half of their door kits. Would you make the doors a few inches shorter than than they suggest to leave a gap above in addition to the mesh?


    1. Paul, mesh sounds good for the top half of doors, without a gap.

      My first polytunnel was 18 feet wide and 55 feet long. That size of structure clearly needs stronger hoops but for your size, the 25mm will be fine.

  17. Hi Charles

    Another really helpful article.

    We badly need a new shed and I was considering a combi-shed-greenhouse, but I am now wondering whether a poly tunnel would be better. I would need to stores tools, electric lawnmower and strimmer etc in there. I presume that if the plastic is in tact they are good for this, or does condensation cause issues with metal tools and electrical items?

    1. Cheers Richard, and it’s a good idea, with the proviso of some condensation, which would be less if you leave the doors open, as we do for vegetables, at least some opening. That leads to the second point which is that it can’t be secure, is not like a lock-up!
      Good value in £/sqm, and dual use!

  18. Hi Charles, I had a new polytunnel from Santa which hasn’t been erected yet. I am 850 feet up on the fringe of moorland in Teesdale. We have a north to south slope and west to east. We are surrounded by trees but there is enough space to enjoy good sunlight. Which way would you put the tunnel up please? The wind is pretty bad here as you can imagine as there is nothing to stop it as it rolls over the pennines. I was hoping for the tunnel to act as a windbreak so that i could grow some vegetables at the opposite side.
    Do you think it is possible to grow vegetables at this height with your method please or will the compost blow away? I placed cardboard down without the compost and noticed that we have 1000’s of slugs. how would you deal with this please? The land has had light use by cows for years. I feel like I have a major challenge on my hands and would really appreciate your help. Is this extreme gardening? If you would like to visit or run a course here you would be very welcome. Thank you ever so much Charles for the wealth of information, inspiration and motivation. Warmest regards.

    1. Yes Karen, extreme! I would run the polytunnel up and down your slope and so north-south if I have understood correctly. Beds up and down the slope.

      I guess your prevailing wind is Southwest so that works for the polytunnel. It won’t provide much shelter, because the wind just swirls around in my experience. It may be worth looking at some kind of windbreak in made of netting.

      Slugs are always a problem at the beginning because they are eating the decaying vegetation of grass and weeds. If your compost on top is good, of 10 to 15 cm depth, plants will be strong and the slugs are less interested in them. But go out at night with a torch and knife to reduce their numbers. Good luck!

  19. Hello Charles,
    I’m just moving my tunnel onto a bit of pasture land, and have plenty of cardboard.
    I see you tried compost under and over the cardboard, and say just under seems fine, but my question is, do you plant through holes in the cardboard?
    We are into the growing season and I have got time for the weeds to die off this year, so think I will need to leave it in situ.

    1. Ann, sorry may have misled you and best option is cardboard on the ground, then compost on top. You can do that the same day as planting into the compost.

  20. Hi Charles
    Thank you very much for your really useful article. I’m about to purchase my first polytunnel (10′ x 15′) and intend to trench the polythene. People love telling me scare stories of polytunnels being blown away and getting storm damaged! I note you installed a polytunnel with base rails and trenching. Do you think I need to pay the extra for the base rails or do you think the trenching alone will suffice? The site is not overly exposed. Also, do you feel it is worth paying extra for screw anchors rather than foundation tubes and, again, is the over the top?
    Your advice would be much appreciated. Thanks, Karen

    1. Hi Karen
      If you are digging a trench for the polythene, you need only foundation tubes with no anchor plates. And you don’t need a base rail! It’s pretty straightforward in fact, sounds good that you are not too exposed. Good luck

  21. Hi Charles, great article and some great advice. I’ve just purchased a half acre plot, fairly steep sloping and orientation is E-W. Plan was to put a thinner poly tunnel in to limit the amount of land I need to level, and N-S orientation isn’t an option because of the slope. What width tunnel would you recommend, and what bed set up inside?

    1. I can’t say because it’s entirely your choice according to how much work you want to put in, and how much produce you want to grow and it sounds like an exciting project!

  22. Hello Charles, thank you so much for this advice. I’ve been growing veg and flowers in raised beds for ten years and I’m finally thinking of getting a polytunnel as Up till now I’ve grown my cucumbers, aubergines etc in small plastic greenhouses and now I’ve raised melon seedlings and nowhere to put them! My poly will be on a bed of chalk and flint, dumped from digging out a swimming pool. Our soil is generally very chalky and poor anyway. My raised beds all have weed suppressant liners. Which actually came with the bed kits. You say I think, never put soil on top of these fabrics.. I presume that is so you can take advantage of organisms in soil beneath? As usual, I was going to put weed suppressant on the floor of my poly. Then raised beds on top. What would you advise please?? Thank you so much!

    1. Nice to see this Annie and pleeeeease don’t put that horrible plastic on your soil, and under any beds. It’s truly crazy that anybody recommends that. It is stopping roots of your plants from going into the soil below, and it is stopping movement of otherwise healthy soil life in both directions. It’s turning your beds into containers sitting on top of the soil and not part of it. Just give it away and he has no plastic there. There is plenty above!

      1. Hello Charles,

        Firstly, thank you so much for all the inspiring videos you have posted on YouTube, and this very interesting article on setting up a polytunnel.

        I recently purchased a Northern Polytunnel, 30ft by 12 ft. I laid corrugated cardboard on the ground topped with municipal green waste compost. As much as possible I’ve been avoiding the use of plastics (although I have to say this latest delivery of municpal compost is riddled with small pieces of plastic), so I didn’t want to use any weed control fabric.

        The cardboard I put down seems to have been insufficient as weeds have easily grown through it in places. The tunnel has screw anchors, so although I didn’t need to trench the polythene, I did leave a c.15cm skirt to push into the soil to form a barrier to outside weeds, although I haven’t done that yet (the soil was baked hard in April and has been sopping wet so far this month). But that’s top of my list of priorities.

        Any advice as to what I can do with these weeds that are coming up inside the tunnel? If I continue to pull them up, will they eventually give up? I really don’t want to use a membrane. I have 2 raised beds (14″) on one side of the tunnel and will put in more on the other side once they are delivered, but I’m wondering if this issue with weeds will resolve itself.

        All the best,
        Michael Armstrong

        1. Yes corrugated cardboard is pretty thin and not so effective against weeds. If you have some more you could lay it on top as a secondary weed barrier which will soon decay, and give you some respite.

          I would not bother with wooden sided beds in a polytunnel, because the thickness of wood uses precious space. And I would use thick cardboard from sturdy boxes as weed barrier for the rest of the polytunnel

  23. Hi Charles,

    I’m thinking of installing a polytunnel of 19ft x 60ft. It will have large double doors at both ends. Will this be sufficient for ventilation? Should I go for a 23ft x 50ft option instead for better ventilation? Thanks

    1. An amazing coincidence Tom because I was just writing about this and about how my 42 foot Polytunnel does not have sufficient ventilation for tomatoes in the summer, from just the two wide end doors.
      In winter it is fine for leaf vegetables, in cooler conditions. I can tolerate that because winter vegetables have more value for me then summer tomatoes et cetera.
      Otherwise you need to look at side ventilation, probably just one side with mesh, not too much.

      1. Hi. My polytunnel is 25 ft x 18 ft with a single door one end and a double door the other with mesh on one side. It gets incredibly hot in summer with a high of 55 degrees last week and regularly in the 40s. We bought a large fan but that seems to have made little difference. Any ideas?

        Also, it traps insects a lot and they die as they can’t escape. Is this normal or how could we alter it to let them escape?


        1. Difficult but I would have double door both ends.You have mesh so that heat puzzles me, I have doors only and no mesh, 42ft long, not suffering such problems, maybe my tunnel is higher.
          Perhaps your climate is too hot for a polytunnel, I don’t know if you are UK.

  24. Hello Charles – I’m an avid fan and attended one of your courses a few years ago at Homeacres. I am just about to order a Firsttunnels Polytunnel following all of your advice, thank you. The space I have will fit either a 10ft wide x 25 ft long, or a 12ft wide x 20ft long. Which size would you recommend please?

  25. Hello Charles,
    My guilty secret is that I’ve had an un-erected polytunnel for about 20 years – all the necessary hoops, rods, tape and plastic skin. The skin has never been unrolled and so has been unstressed and in the dark all this time. Do you think it will have aged, or should it still be OK to use it? I’m reluctant to splash out on a new roll, though it would be very annoying to get it all erected and then have the plastic fail.
    Best wishes,

    1. Wow, vintage!
      You could tell by opening and just feeling a corner of the plastic, that it should be tough and not at all brittle. I really don’t know though, 20 years!! It may be okay… And good luck

    2. I feel that in 20 years the manufacturers will have improved polythene covers no end and today you would have a superior product. I would treat myself to a new cover.

  26. Hi Charles, thank you for providing such a great resource of information online. We will be shortly recieving our first polytunnel for an allotment plot. We would like to try the no dig approach, but the plot we have been given has quite a bad problem with Horsetail (Equisetum arvense). Would you recommend anything different from your standard cardboard and compost approach? Kind regards, Dan & Ginny

    1. Nice to hear except for the horsetail and it’s the same approach, but with repeat pulling and then more repeat pulling, for a few years. Plus special to mulch around the edge of the poly tunnel to stop it spreading from outside

  27. Hi Charles, I’m planning on erecting a polytunnel on what is currently a grassy field. Would your usual method of cardboard and compost be sufficient to eradicate the grass?

  28. I have a 20 x 9 ft Solar Tunnel, moved from my last garden. My new garden is narrow and mostly shaded by trees and I’m wondering if it’s even worth erecting my tunnel, though one end would get sunlight during part of the day. The cover is the type with green webbing, which seems to cut down the light. I’m not sure if I can get a clear one from Solar Tunnels. Do you think I should forget the tunnel and instead just shelter some of the crops with cloches? Thank you.

    1. Lorna, I agree with you, it sounds not worthwhile. Also I suspect that the soil will have many tree roots which suck moisture in the summer so not ideal!

  29. Thanks for all this information on poly tunnels. I have just taken over an allotment with an old poly tunnel. Plastic covering fine and I am cleaning it up. Just not certain what I do about the soil. Do I just add new compost or do I need to dig out some of the old soil! Thank you .

  30. Help needed on finding someone who can replace cover and sides of existing poly tunnel.We can source the materials needed but unable to find anyone to fit the replacement cover. We are living near Settle in North Yorkshire.
    Thank you
    Rosemary Crabtree

  31. If a polytunnel is going onto open, grassed, ground for a period of 8months (before being relocated again) and is going to be used for container plants, what would you recommend for the ground surface inside the polytunnel?

    1. Wow that is a short period of time! I would use a large sheet of black polythene, which you may be able to get for free from say a local farmer. Even if you have to buy it, you can reuse it several times afterwards, just make sure it is thick enough I think 600dpi, to exclude light.
      Cardboard with its overlaps would I fear result and quite a few slugs.

      1. Hi,

        im putting up a new polytunnel, previously i have laid ground cover to suppress weeds and then moved soil on top. However where the new polytunnel is going, was a former chicken run, with limited weeds/ grass, i was wondering therefore if i need to lay a ground cover, or i can simply use the soil as is, by the way i am trenching the polytunnel into the ground which should stop weed spread from the sides.

        1. It sounds like you do not need groundcover membrane, and never put soil on top of anything like that. So yes, go forwards as is, burying edge is good

  32. Hi there a brilliant article thanks!
    I notice green plastic polytunnels are a bit cheaper than normal clear ones, is there any disadvantage in buying a green one?

    1. Thanks Conor, and yes the green plastic admits less light and light is very important. Also from what I see it is less strong and therefore likely to split in high wind. It’s worth investing in strong top quality polythene.

  33. Hi, sorry I’m getting a bit confused about orientation. I am getting a tiny poly tunnel (3 x 2m) as I have a small garden. The only place I can really put it is on the E side of the house. I have two options orientation-wise 1) N-S where door way would face S and ventilation would be along western side or 2) E-W where door way would face W and ventilation would be along N side. Any advice greatly appreciated. Thank you

    1. Btidget, for a very small polytunnel like that, I would not worry in terms of shade and ventilation and I would place it in the way that fits best alongside your house and is easiest for you to access.

      1. Question about the same size poly tunnel that I’m looking to buy. Firstly is it worth getting one this small and are there any considerations? I’m a first time veg grower and was initially looking for something to keep my dog off the patch but can see there are many other benefits too! Any recommendations where to buy one too? I actually need something about 3x3m which I’m having trouble finding on the internet. Thank you

        1. Square ones are unusual, I would go for 3 x 5m, sou will like the extra space.
          Best Search, see what you like.

    1. I don’t know Alan, and I don’t recommend them for a polytunnel unless your site is well protected from the wind

  34. Charles, is it possible to grow tomatoes in the same polytunnel beds year after year? I realise that they are being planted in new compost each year, but the deep roots will essentially be in existing soil and I worry about a potential buildup of problems.

    Have been growing tomatoes in my 10th’ x 6’ greenhouse for 10 years but change the compost each year – an easy job in the small greenhouse but something I wouldn’t want to do in our new 25’ polytunnel.
    Many thanks for all you inspiration, we’ve been practicing your no-dig system for a few years now

    1. Cheers Tom and yes you can.
      Maybe after 10 years there could be issues.
      In my greenhouse this was 8th year of good tomato plants.

  35. Hi Charles, you have truly been an inspiration for us to set up a fairly large veg garden and also a 14 by 35 feet polytunnel. And we’ve had lots of beautiful organic veg this year. As first time grower doing no-dig, the results had been phenomenal but I do need your help and advice on the maintaining the plants inside the polytunnel and on the polytunnel itself.
    1) We laid down quite a lot of cardboard to suppress the grass/weeds but didn’t realised, given the dry summer this year, that our polytunnel is actually built on a very wet and soggy area. With the advent of the rain in autumn, there’s quite a lot of cup fungus that have grown on the mushroom compost we have inside the polytunnel. How dangerous are they to the veg inside the polytunnel as I noticed brown spots on the cauliflowers and rust appearing on the leaves of the leeks? How can I prevent the growth of pig-ear/ brown cup fungus in the polytunnel?
    2) Why is there rust on the leeks as I watched your video on the garlic and garlic not affected by rust inside the polytunnel so I’m wondering what we have done to have caused the rust?
    3) We’ve got a current infestation of aphids (green ones/ winged ones and red/ brown ones) inside the polytunnel and we are losing the battle with just cleaning the leaves and spraying with a mixture of dish-washing liquid and garlic. They have spread to almost all the plants in the polytunnel including the bulb fennel plants and I thought they don’t like the smell of fennel. Can you kindly advise the quickest method on how to stop the infestation organically?
    4) Will the aphids overwinter in the soil and then come back again next growing season? (Note: the polytunnel is full of veg at the moment hoping to tide us through winter till the next growing season) How can we get rid of all the over-wintering aphids and larvae?
    5) Saw your video/ blog on cleaning the outside of the polytunnel (or is it in your book as I’ve a few of your books as well). What organic cleaning solution do you use for the outside of the polytunnel? Also how to and what solution would you advise to clean the inside of the polytunnel?
    Your advice will be very much appreciated.

    1. Nice to hear Jan, excellent for a first year.
      The boggy soil will improve in time thanks to soil life, but is a reason for plants struggling a little, and then aphids are attracted to them.
      1 That fungi sounds fine to me, it has decomposition work to do, just cut off the mushrooms when seen to clear space
      2 I have some rust on garlic, not a lot, should be ok and pull off the lower leaves to compost
      3 Best remedy is long term, add more compost to build fertility, soap etc is temporary only
      4 You can’t “be rid of them” but need stronger plants which don’t interest them
      5 Just water!

      1. Hi Charles, really appreciate your reply. Honestly, we wouldn’t have started our organic veg garden if we didn’t come across your information and books on no dig so thank you and Stephanie for setting us on this path. I think I’ve watched all your videos before embarking on this.
        To clarify with just a few more questions:
        1) Can the cup fungus be added to the compost?
        2) The plant leaves (eg. Cauliflower leaves with the aphids) should they be thrown away in the bin or can they be added to the compost? Will aphids / larvae survive composting?
        3) Are there plants that attract more aphids eg. tomatoes/ chilli plants? in which case I believe your book indicates companion planting such as basil/ marigolds? Will they help?
        4) I know your advice is to add organic compost plus homemade compost (not ready yet!) and mushroom compost and manure to add fertility. Will only mushroom compost be sufficient to add fertility or must it should be a combination for optimal soil fertility?
        5) We got a few tons of mushroom compost this year and added about 15cm to all the vegetable area. Do we need to top up for the next year’s growing season for added fertility or will it ok for one more year?

        1. Great thanks.
          All damaged leaves and plants can go on the compost heap.
          Yes dwarf French marigolds are great companions plus beautiful plants.
          Any compost brings fertility. You may not need to add any for another year, but 2-3cm will be nic food for soil organisms.

  36. Hi Charles! Great advice on starting out with a poly tunnel. Re the ventilation at the top of the doors. Do you mean leave a permanent gap? So not a gap that needs to be somehow covered during the depths of winter? Also, are you happy to recommend a poly tunnel company? I’ve just done a google search and First Tunnels looks good. But you may know of another.

    1. Hi Sally, and yes First Tunnels are excellent. The base rail is good so far here.
      And yes I have a permanent cut hole each end, all through winter

    2. Hi Charles,
      Re Ventilation at the top:
      I live about a mile from Strangford Lough and am 350 feet above sea level. Although I am now reasonably sheltered, it is a windy site and as I am on farmland, and on a moraine, I am also surrounded by long stretches of whin. As a result we get lots of wasps and flies. If one ventilates as you suggest, being above sea-level, is there a chance that the wind will ‘catch’ the venilation area and b) would it not be a direct route into polytunnel for wasps and the like?

      1. Perhaps Brian, but that would not worry me at all because we need lots of insects and in my experience they always balance out. Maybe you get a few birds coming in to eat them et cetera

      2. Hi Brian, we have occasional high winds here too and I have never found any problem of wind blowing out the poly tunnel, from flowing in those spaces.
        As for insects, I would say it’s not possible to exclude them, nor desirable – many of them serve useful purposes so I would not worry, for example this summer we had great melons in there, and there were wasps flying around as well.

    1. These hold warmth but are expensive. Are perhaps difficult to clean after a few years, can last a long time before recovering is needed.
      Keder greenhouse for example, solid, storm proof, and expensive.
      Normal plastic tunnels serve well in most locations. I am happy with mine from First Tunnels.

  37. Hi, Charles,

    First things first – I just want to say thank you for all the incredibly useful information you make available both here and on YouTube. Inspired by you, my wife Carole and I are now moving our allotment over to no-dig.

    Our allotment is pretty small (30ft x 45ft) and 10 years after our association first secured the use of the land*, our Parish Council has finally agreed to allow plot-holders to have polytunnels, however, we are restricted to maximum dimensions of 2m x 4m or 3m x 3m – both substantially smaller than we’d like but beggars can’t be choosers.

    Clearly, the latter size gives us one extra square metre of space but I’m interested to know if you have any views on whether a rectangular footprint (albeit smaller) has advantages over a square footprint.

    I have a second more general question, too, if that’s OK. We accept we’ll never be able to grow enough fruit but do you think it’s possible or reasonable to expect for us, using no-dig methods, to become self-sufficient in veg on a plot of this size? The kids flew the nest some years ago, so it’s just Carole and me to feed. We intend removing the boards from most of the raised beds and believe this should help bring more of our plot into production as paths will become narrower and, in some cases, no longer needed.

    Apologies for monopolising your time!

    Many thanks,

    Best regards,


    *Can’t tell you how much I wish I’d discovered no-dig ten years ago – the money and time I would have saved, not having to build and then replace raised beds!

    1. Thanks Ozzy and I would go for 3×3, the extra metre!
      You should be able to grow almost all your veg. Avoid low yielders like Brussels sprouts and asparagus.
      Do lots of inter- and succession planting. A good project.

      1. Thanks, Charles – will be guided by you!

        Interesting comments about the asparagus – we already have some that were a gift but they haven’t done well and I was planning to move them but will have to rethink – and the Brussels sprouts (one of my favourites but you can’t have everything!). I take it we’d be OK with other brassicas?

        Thanks again,

        Best regards,


  38. Just a quick question I am about to get a Polytunnel for flowers mainly should I place it sideways to sun or ends to sun. Thanks

  39. What do you do to stop it getting too hot in summer? Our greenhouse reaches 30+degrees for long periods of the day. Were in south Cotswolds.

  40. I am admired with your article on tips to buy a polytunnel as myself also got into problem several time while choosing the best polytunnels. I really appreciate your hard work writing these actionable tips to read before buying a polytunnel.

  41. Do you have any experience of these carbon fibre polytunnels? I’m looking at those As a permanent fixture, but obviously I’ll anchor it well… just can’t seem to find much out about them so just presume they’ll have the same benefits as a polycarbonate greenhouse as opposed to glass…..

    1. I am not sure Nicola, know they are expensive and you could buy twice the size polytunnel with ordinary plastic, that would be my option.

    2. Hi Charles, thanks for all your useful videos and tips. Would you still recommend just digging in the plastic or do you think the base rails and digging in the excess is a better option? Thanks

      1. Hi Alex, thanks and a good question since my current tunnel with base rail is working well, so it’s a good option. However we did dig in a skirt of polythene below the rail to keep out weeds and slugs, and rubbish. It’s stuck in about 10 cm/4 inches.

  42. Hello Charles,
    We stay in the HIghlands , a very windy area!
    We are looking into getting a polytunnel measuring 6ft wide by 18 ft , we can go up to 20ft , this will hopefully be placed North to South and alongside the croft wall, with a banking of small trees the other side so fairly protected from snow and wind. A lot of firms have mentioned base plates, the area we are planning on putting it is on grass, can we do without base plates what is needed to make it sturdy. Also are two doors needed can one door be sufficiant. Thank you.

    1. 6ft wide is tiny! and yes two doors needed. unless you cut a small vent hole one end, ask the suppliers, probably needs two doors.
      Needs a hole dug for the plates, no way around that. Grass regrows fast!

  43. Charles ,

    I am erecting a 16x27ft polytunnel soon – I am keen on applying your no dig technique(which I find extraordinary may I add), though do you recommend this with raised beds or just apply a few inches of compost on layers of cardboard and start planting ?! Thanks and keep up the excellent videos on YouTube

    1. I would not lose precious polytunnel space to wooden sides, just no need.
      Cardboard is only if you have thick weeds to deprive of light.
      You will grow a lot of food.

  44. Thank you very much Charles will do. Have you seen this work out well? Or do you think I should take the concrete out? Best Jonathan

    1. If I had time, I would always take the concrete out.
      I have seen successful beds on paving slabs, with gaps allowing water to pass though.

  45. I would like to have a 10′ x 20′ polytunnel for growing vegetables( not root apart from beetroot) salads and squashes but the best place to locate it is on concrete( an old silage pit ) This means raised beds inside – is 12″ soil enough? and how do I manage drainage issues? A layer of gravel at the bottom? Or should I either break up the concrete – or find another site? Many thanks

    1. Hi Jonathan, yes this is possible, if you can anchor the tunnel to the ground!
      Definitely break the concrete to allow water to pass downwards. Cracks in the concrete should be enough, check first to see how deep it is and whether you can break it!

  46. I have recently bought a house near Sheffield with an acre and a half of land which was used by the previous owner for horticulture. My plan is to have a no-dig vegetable garden of half an acre, growing “in season” produce for a local restaurant. There are two old 10m x 30m polytunnels on site which appear to be too big for my needs. Approximately, what size of polytunnel will I need to supply the vegetable garden with sufficient seedlings to allow as many crops as possible per year? The main crops will be staked beens, leeks, onions, broccoli, garlic, lettuce, cabbage, aubergine, courgettes, beetroot, spinach, cavolo nero, and peas.

    1. Yes Paul those are big tunnels.. for propagation, you need say 10 square metres/110 sq. ft.
      But aubergines need polytunnel conditions to grow, and the tunnels will be useful for winter vegetables especially eg kale and lettuce.
      Hope you can open soon 🙂

  47. Was wondering if you’ve come across the Keder Greenhouse and what you’re thoughts were on this type? They use a unique Kederbahn bubble plastic and rail system which seems quite good. Apparently they are more cost effective than a traditional glasshouse, and also stronger and more durable than polytunnels.


    1. “Cost effective” hmm, they are expensive Simon!!
      May be worth it for cold and windy areas, otherwise a strong-hoop polytunnel is most cost efficient, easily

  48. What about soil never getting washed by rain under polytunnels? Can this be an issue in the long run? Such as salt accumulation..is that a thing? Thanks for another helpful article

      1. Thanks for your answer. Which size tubes you ended up choosing after realizing the 1in was too light for exposed sites?

  49. I forgot to ask if the tunnel should be aligned (parallel) to the direction of the winds?

    Thank you so much for your articles!

      1. Hi Charles, when you say ends do you mean where the doors are?
        Many others on the net are saying not to do this, can you tell me why you recommend this from your experience, if I understand you correctly

  50. Hi Charles, this is such a helpful article, thank you so much. You say orientation North to South. Would you think a slight north facing slope would impact heavily? Alternative is to go across the slope east to west. With a south-west prevailing wind, how would this affect orientation? Also do you know about need for planning permission for polytunnels? What is the max size before needing planning? Many thanks, Olivia

  51. Hello Charles, I live on high ground 8 miles from the sea and I have 3 20×10 polytunnels but have not seen put them up here because one flew away at a more protected site. I might get a profession polytunnel company to put up a new one. What is your advice please. Also in answer to your previous correspondent, i had a small polytunnel and it was marvellous, you can grow a lot of especially if the beds are reasonably deep.

    1. Nice to hear Mel and on your windy site, it’s probably worth paying professionals to erect the tunnels.
      First Tunnels did a fantastic job on mine, apart from a small mistake on the irrigation, but that’s a detail 🙂

  52. My allotment field only allows tunnels up to a max of 3.5 by 2.5 meters, do you think that this size is worth having. Took on a second allotment recently and used no dig with cardboard and leaf mold and now have a weed free set of beds although we had teething problems as the local foxes and cats kept digging it up and letting the weeds through.

    1. Yes John it is better than no tunnel, however the small ones are sometimes not storm-worthy.
      Well done on your no dig.

  53. What would we do without Charles
    I am completely addicted after meeting a colleague who told me about him and no dig while on a course in Coventry University in Social and Therapeutic Horticulture
    He has changed my life for the better ….
    It really works better than all the other methods I m sure after trying things myself as he recommends…
    Proof is in the pudding
    Joyce Fitzpatrick

    1. Hello Joyce, and thanks so much for writing, and I am happy to help.
      I’m pretty sure that your contact was Lara, who also is special, and that course sounds so worthwhile.

  54. I’ve never done polytunnel gardening. I live in South Carolina, USA on the coast. What would you suggest? What brand? Thankyou

    1. Hi Barbara, afraid I do not know the USA brands but you call them hoop houses. Look for one with sturdy metal hoops say 2in diameter in case of high wind, I suggest 14ft minimum width and any length, make sure you have water available.

  55. Thank you so much for this wonderful article!

    I am a beginner gardener and my allotment is not close to the house. Should I buy a tunnel or a small greenhouse (my garden as well as all the alotments around me have a rat problem that becomes more difficult in the winter and rat poison or traps are not 100% efficient)? The greenhouse would have glass walls, aluminum supports and a brick and concrete foundation on top of which we would put soil and compost in oder to keep rats out.


    1. Alexandra I would watch my video comparing greenhouse and polytunnel, for your small garden I would choose a greenhouse

      1. Hi Charles what is the minimum size of polytunnel you can build and it still be worth it?
        Am hoping to squeeze on in on my allotment. Have a space of maybe 7ft by 3ft. Too small? Any potential issues you foresee?

        1. May I smile? I love your audacity, 3ft width and you can hardly turn around inside!
          It’s possible but would be expensive per square foot.
          Hope you can go bigger 😀

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