Putting up a polytunnel: fresh fruit & veg all year round

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Posted Mar 8 2015 by Paul Jennings of Criafolen

There’s loads of information around when you come to put up your polytunnel. The one I’ve just finished erecting came with really good instructions and the company website provides a whole host of instructional videos for the fiddly bitshttps://www.firsttunnels.co.uk/tunnel_vision.asp.

I should say that putting up polytunnels is nothing like riding a bike or swimming. Years ago, when I worked as a grower on organic farms, I put up some really big tunnels, but I shouldn’t have thought that that necessarily stood me in good stead for avoiding all of the potential pitfalls this time around.

So, never try to put up a tunnel on your own. I already knew this. I really did. But this was only a small tunnel, right?

And when you do have help, as I did for putting on the plastic, try to get one more person than you think you’ll need. It’s well worth having to buy the extra pint or hand over the extra bag of veggies just for the extra pair of hands on the team.

I found myself wrestling with hoops and desperately wishing that I had someone to hold the other end of the tape measure. There is no way to be as accurate when you’re on your own and especially on an imperfect site – which is what you’ll have unless you’re putting up your tunnel on a flat lawn – the job can very quickly become a sort of firefighting exercise correcting problem after problem.

polytunnel interior

Also, make sure that you have all of the tools you need. Make the instruction booklet your bedtime reading for a night. Write a list. If in doubt, take an extra spanner and a range of screwdriver sizes.

Charge your drill!

Setting out is the most important stage. A polytunnel is easily put together, but don’t rush the preliminaries. It’s only a tunnel, and I’m a great believer in the “close enough for a country job” philosophy, but you’ll have to look at the off-centre ridge for a long time once it’s up. And yes, my new tunnel does have an off-centre ridge!

Struggling with hoops is one thing, but even an imperfectly erected tunnel will transform your growing. Propagation space and four season gardening are invaluable advantages of tunnels. As a small scale grower I know that the productivity of my garden is multiplied enormously by even a modest tunnel space.

The value of protected cropping can be easily seen by looking at the British strawberry industry, booming thanks to polytunnels. The thing is of course that whilst for growers tunnels can be a godsend, for people who have to look at them they can be a glaring eyesore, and we all have to wonder about the polythene. I’m supposed to be an environmentalist, what am I doing using a vast sheet of polythene?

polytunnel front

Polythene is made from crude oil in a gasification process. It’s not nice and it’s certainly not sustainable. When we’re done with our polytunnel cover, five years down the road or so, it has to be disposed of. Fortunately, at least these days it can be recycled: http://www.solwayrecycling.co.uk/farm-waste-recycling-system/polytunnel-recycling but nonetheless, this kind of protected cropping is energy intensive.

So growers will argue that their tunnels reduce food miles, and also that they allow for less use of fungicides and pesticides. For me it’s about making my small garden a viable business proposition, well, that and the delights of good winter salads and reliable summer tomatoes. Still, I wouldn’t deny that polytunnels are problematic: they most certainly have an environmental impact and above all they are noticeable in the landscape.

One of the things we can do as tunnel users is try to place them where they will have less visual impact; we can also use plantings to hide them. I’ve nestled my tunnel up against a wood, and I’ve planted trees around my garden; it’s still quite visible now, but eventually it will be much less so.

Protected cropping has always been energy intensive. It’s instructive to look at a walled garden; there’s a lot of bricks and mortar in a walled garden. Also walled gardens were traditionally built with big greenhouses, glass and iron all along their interior south-facing wall. In the days when walled gardens fed whole estates, they used tons of manure every year and enormous amounts of labour. I don’t mean to suggest that polytunnels will ever be seen as beautiful things, but it would be interesting to know if anyone ever complained about the visual impact of a walled garden.

I have friends who talk about using glass instead of polythene and there’s nothing I’d like more than a big greenhouse, preferably in a walled garden. Cost of course, is prohibitive. In any event, if we take energy descent seriously, greenhouses and vast enclosing brick walls are barely more of a long term solution than polytunnels.

polytunnel door

Polytunnels are a transitional technology, in my opinion best seen as a way to get us through a few years during which we establish durable food growing systems. This argument necessitates some other more sustainable strategies for season extension. What could those strategies look like? When the last skin is taken down from the last polytunnel what are we going to do?

Well, we might perhaps at least come up with interesting ways to use the frames, clad them with planks or weave willow in amongst them and thatch them with reed. But as for the advantages of protected cropping, we will need to design for the creation of warm microclimates. If we don’t want or can’t have tunnels, then we’ll need to use courtyards, hedges and windbreaks; we’ll need to use pond placement to warm and to light our sheltered spots, and every wall will have to lend its thermal mass to growing.

Designing microclimates to replace expensive and energy intensive methods of protected cropping is a really exciting challenge; it can also be expensive and energy demanding to put into practice in the first place. This is the puzzle of transition, and we all need to be thinking about it when we’re enjoying stepping out of the March wind into the Mediterranean warmth of our polytunnels.