Erecting a Keder Greenhouse

 In Greenhouse Growing, Grow your own, Polytunnel, Product Review

Erecting a Keder Greenhouse in my new garden was always going to be a big step forward but I hadn’t bargained on just how difficult taking those steps would be!

Let me be clear I’m no DIY enthusiast and, in many ways, if it hasn’t got chlorophyll it’s not something that I’m going to look forward to doing!

I’ve always admired British made Keder greenhouses. They are very strongly built unlike many other polythene clad tunnels on the market.


I must point out that I did negotiate a very small discount from Keder in return for a review, a blog and a few mentions on my Twitter [@AlanEDown], Instagram [@alanedown] and Candide Gardening [@AlanGardenMaster] accounts.

Nevertheless, this is a frank blog of my experience with the Keder Greenhouse so far and is not influenced by this very small [10%] discount.

Keder greenhouse, poly tunnel, polytunnel

Erecting a Keder greenhouse

Ordering and Delivery

The order process was fairly straight forward. With a reduced work force due to Covid-19 lockdown it was not quite as easy as under normal circumstances.

The cancellation of so many garden shows this year meant that I was not able to place my order at a show. I would have preferred to see a greenhouse at one of my favourite shows. I’m particularly fond of the RHS Malvern Spring Show but of course that was cancelled.. I would have quizzed the Keder team on just how easy the greenhouse is to erect.

Delivery was reasonably prompt and very efficient. Each house is made to order and so there was an inevitable delay but that allowed me time to prepare the site.

When the kit arrived on a single neat pallet I was very pleasantly surprised at how well packaged and well thought out this had been done!

Unpacking and checking

It soon became evident that this unit had a lot of parts. Also that erecting a Keder Greenhouse was not going to be done in a few hours!

Parts are generally very well labelled but I found it confusing that I had received a few extra parts not needed for this particular house. This inevitably lead to confusion.

Erecting a Keder Greenhouse on site

I chose a site that was reasonably sheltered and in full sun for much of the day.

This was a bit of a trade off. Since siting the Keder Greenhouse in full sun would mean placing it in a very prominent position in the garden. Although very functional the Keder house isn’t a thing of great beauty!

I chose a site that had good soil and only a slight fall in one direction.

With the occasional help of my wife Felicity I proceeded to erect a Keder greenhouse. This was in between caring for 9 very demanding flat-coat retriever puppies.

With the Coronavirus lockdown firmly in place I couldn’t hire in any help nor get any on site assistance from Keder. As a consequence, and because at times it was too hot to be out in the sun, the construction was a stop – go affair!

Driving the ground fixing rods deep into the ground provided the anchors. These were attached to a wooden frame screwed together at ground level and it is to this that the hoops and polythene cladding is fixed. Each hoop is made of three sections and joined with a further three pieces of galvanized pipe.

It soon became evident that the order of putting all these bits together was going to be critical!

Keder greenhouse

Tomatoes inside the Keder Greenhouse

I should point out that I’m no ‘newbie’ at polytunnels. I once managed a large nursery that had over thirty single span 100 ft tunnels and several very large multi-span polytunnels too. In fact the number of tunnels that I’ve been involved with over the years must run into three figures. However I have never experienced a kit with so many pieces as the Keder!






Installation Instructions

Fortunately a very detailed installation manual came with the kit.

A DVD of a team of Keder employees erecting a greenhouse was also included.

The written instructions were hard to understand [remember I’m no DIY-er!] and I frequently looked at the DVD and the same film posted on YouTube. I found that it helps to look at this in slow speed mode.

A few calls to Keder who talked me through things like extra bits supplied and not needed helped immensely. They also stressed the importance of putting the right fittings on the hoops in the right order.

Continuing the build

Plastic glazing strips, keder polythene, an electric drill

Glazing the tunnel was very difficult.

All went relatively smoothly until I came to fix the glazing strips to the outside of each hoop.

These are supplied cut to length but were not particularly flexible so that any kinks in them were hard to straighten. But when it came to screwing the self tapping bolts through the glazing strip and into the hoops we really struggled. This looked like slicing into butter on the DVD but for us it was a real nightmare! Speed of drill, weight of push and angle of drill bit were all tried and still the threads were stripped. We ended up with some sections of the hoops looking like pieces of Emmental cheese and really worry about this having weakened the structure!

This glazing method is perhaps unique to Keder and necessary to hold the polythene sheets in place.

There are polythene sheets for each section between each hoop unlike most other tunnels where one sheet covers the whole structure. The polythene is twin skinned with bubbles trapped between and this will help heat retention at night.


We persevered and eventually got all the glazing strips and polythene cladding on. But we found it very difficult.


Erecting a Keder Greenhouse

Each sheet is fed into the glazing strips.

The Keder polythene sheets have a beaded edge on both sides. This is threaded through and held by the plastic glazing strip which was so difficult to fix to the hoops.








It’s possible to have an end vent but we opted to have a large roof vent instead. This gave us the opportunity to have a door at each end of our 3 m x 6 m greenhouse.

Fixing the vent in place was relatively easy.

I chose to have the vent open on the side away from the prevailing wind which I felt would lessen the risk of high winds damaging it. It is in any case a very strong unit!

Erect a Keder Greenhouse

Cutting the glazing strip for the vent polythene to pass through.

The plastic glazing strips needed to have a small section cut out of them for the vent. I felt that this was an operation that had an element of self injury risk. Nervously I completed this but wondered whether there was a better way of doing this. I used an exceptionally sharp handmade knife rather than the recommended Stanley knife and had much better blade control.


A Bayliss Autovent Mk 4 was supplied with this kit and once installed has worked very well.

I was disappointed that the washers supplied were too small for the pre-drilled holes in the Keder vent frame. Fortunately I found others that did the job.



As already mentioned we opted for a door at each end.

It seemed odd that these well made doors were fixed by hinges to the batten on the door frame. Why not to the door frame directly? The battens had already split in several places. To attach a door to it seem to be asking for trouble.

erecting a keder greenhouse

The door hinges

I fixed my doors directly onto the door frame. That has the disadvantage of preventing the door from opening right back.

Normally it’s fixed to the hoops with the chains provided.

It also means that my doors can be caught in gusts of wind and perhaps damaged. I’ll need to find a means of preventing that.




This is a very strong greenhouse! It’s well made and uses high quality materials.

I found it bemusing that so many bits were needed to construct what is after all a very simple structure!

It certainly pays to check and double check that each bit is put on in the right order!


What I’m going to grow

I’ve planted tomatoes, squash and chilies so far and I’ve plans to grow some cut flowers later.

I know that this is going to be a great growing space. I’m looking forward to the extra heat retention that’s promised by the Keder’s special glazing. As with most polytunnels the light levels inside are excellent.

I’ll be blogging about my experience with this Keder greenhouse and also the crops that I grow in it over the years. Do keep an eye out for those.

I’ll soon be picking tomatoes and the chilies are coming along well. Incidentally, if your interested in growing chilies I’ve written about one of the best places to see a huge range of chilies growing here.

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Showing 6 comments
  • Ian ball

    Hi I’m thinking of getting the same size tunnel as you. Could you tell me if it’s worth the money and would you recommend getting help to put it up or pay them to do it? Lastly how long did it take you? By the way I am a gardener working at wakehurst (part of Kew ) looking for something in my own garden.

    • Alan Down

      Hi Ian
      Sorry for the delay in replying…..I’ve been very busy in the garden! I would recommend buying a Haygrove polytunnel rather than the Keder tunnel unless you are siting it in a very exposed place. It took me several days and a lot of cursing to erect the Keder tunnel. At the time I bought mine Keder were not able to erect any tunnels as demand for them [during Covid lockdown] was very high. Haygrove will erect their garden tunnels for you. Alan

      • Tim Crossman

        Alan, thank you for recommending our tunnel! I would like to take you to ask about “exposed location” We have our tunnels in the most exposed locations across the U.K. and to our knowledge never lost one through wind damage. I would hope our reputation for strong robust tunnels is well regarded by all of our customers!! 😀

        • Alan Down

          I assume that you mean “take me to task” rather than ask? Assuming that, then I am reassured that your Haygrove tunnels also perform well in very exposed locations. To date I have only seen the very robust Polycrub in what I consider most exposed locations vis. the Outer Hebrides. I think you know that I’m a fan of your tunnels!

  • Ruth Harris

    Do you make anything that would fit into the space I have?
    1 metre deep by 1.40 wide? And tall enough to stand up n.

    • Alan Down

      Hi Ruth, that does sound like a tall and yet small tunnel. I don’t make the Keder Tunnel [or any other polytunnel] and so your question is best asked of a tunnel supplier. Alan

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