Greenhouse or Polytunnel?

We saw some greenhouses advertised at market last week, and since we’ve just sold Quinta das Limpas we can afford a ready-made one. A 12m2 aluminium framed greenhouse with glass sides and polycarbonate roof, with double doors, 3 windows, gutters for rainwater harvesting, delivery and installation, will cost around 2,000 euros. That’s a LOT of money!

I don’t know where to get a ready made polytunnel in Portugal, or how much they cost (anyone?). So the other option is a home-made polytunnel using either bent plastic pipes or bent mimosa/eucalyptus sourced from our land. This is certainly the cheaper option and, at first thought, the greener option.

But is it? How long will the polytunnel last compared to the greenhouse? How often will the plastic need replacing, and how easily available/expensive will the plastic be in the future? How do we dispose of old/torn plastic? Do I want to spend time every year patching/rebuilding a home-made polytunnel?  I think a greenhouse would be a lot easier to clean – should that be a big consideration?  And of course, which is better for growing in – greenhouse or polytunnel?

Hmmm … I really don’t know. Which is why I’m posting this here, in the hope that anyone reading this will leave a comment with your thoughts (please)!

Four Season Harvest

The Polytunnel Handbook

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9 Responses to Greenhouse or Polytunnel?

  1. admin says:

    Well Gav has just thrown a spanner in the works with this:

    “Go for polycarbonate whatever, most expensive but the only fire-resistant option – check out for some ideas too – they have some great features in their greenhouses that could be translated to a self build xx”

    Now … if I could get one of those in Portugal …

  2. Nuno says:

    Olá Sophie,

    I’ve been enjoying the blog for a while, congrats on the new look.

    In Agrovida you can find some available greenhouses (by Rovero):

    An advice someone gave me was to check out the local Grémio de Agricultores or Cooperativa Agricola for second hand sales, list is here:

    Or maybe second hand sales on online ads like these:

    Hope you can find something, cheers!

  3. As an ex-owner of 2 greenhouses who had to rebuild both (very carefully) from the ground up after a particularly violent Christmas storm where all we could do was sit indoors listening to the sound of breaking glass, I can certainly tell you that greenhouses are not necessarily likely to last any longer than polytunnels!!

    Like the new look to the blog!

  4. Derek says:

    As a current glass green house owner i can tell you we have only had to replace 3 “panes” in the three years we’ve had it. You do have to wash it to keep that nice transparent effect,…sans the green mildew, but also ive noticed that our aluminum frame is oxidizing at structurally vital points, and wonder if this will be a problem in 2-3 years. Our green house is on a wood frame, which is rotting and will need to be replaced maybe next year, and every winter we get one serious hail storm, and one snow dump (here in the armpit side of Denmark), that tests the roof panes.
    We have thought about it and like the idea of being able to ‘break-down’ the poly tunnel,…use bamboo for a structural material, and move/store it entirely to get it out of the summer sun, and to ‘cycle’ the underlying earth. Our vote is for the polytunnel.
    Of course the concern for longevity of the ‘poly’ is noted, but why use polyethylene. Is it possible you could find a source of discarded transparent sail material or kite material (nylon, polyester, other?) the rest of the tunnel is so cheap maybe searching for a good long lived material that cost a bit more but would still provide that green house effect would be worth it.
    Just an idea,

  5. dylan says:

    HI i’ve had good success with the homemade blue pipe tunnel, if you want to use less plastic face it south and use wood for the northside, it doesnt get much light anyway..
    plastic obviously degrades and won’t break down in the environment for a couple of hundred years- it just gets smaller and smaller. so glass is probably a better ooption. There’s a lot of embodied energy and environmental damage in aluminium…
    tough choice..

  6. sophie says:

    thanks everyone for your comments, keep ‘em coming!

    at the moment i’m leaning toward the polytunnel (to be truthful i was from the beginning, if only because the ‘real’ ones are just too suburban garden for me!).

    derek – i can get sail material but it’s VERY expensive. the plastic they sell in the agricultural co-op is designed for polytunnels so it’s reasonably long-lasting and cheap.

    dylan – thanks for the comment. just visited your blog – looks very interesting, i will have a proper read later! also will read the Solar greenhouse resource linked from your blog which looks useful

    if anyone’s interested in more comments, there’s also a discussion going on over at facebook

  7. andy says:

    update: the weather has cooled, so we went to town to get some black plastic pipe to build a poly tunnel – using old scaffolding as the bottom walls/supports.
    polycarbonate 6m lengths are less than 5 euros each, and will last longer than the ‘water pipes’ i intended to use.
    the solar resistant plastic cost us 35 euros for 8m by 8m.

    so a small home-made polytunnel is going to cost about 50 euros, compared to almost 2000 for a greenhouse! will post some photos as soon as the pipe is delivered and we get it up.

  8. leen says:

    Joaõ in Chão sobral mead a nice one with this material that they juse for roofs,it is long lasting ant rains clean but is expensive .Maby he can tel us the name

  9. leen says:

    so it is this polycarbonate gleasing thing .

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