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Thread: Greenhouse vs Polytunnel

  1. #1
    Lymmguineas is offline Germinator
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    Default Greenhouse vs Polytunnel

    I've been envious this year of all the stuff that other people on the allotments have produced in their greenhouses.
    I'm thinking of getting one next year but for the size I would like they seem quite expensive.
    I've also looked at polytunnels and they are clearly a lot cheaper.
    Can anyone help me out with some advice please? Apologies if I'm asking some naive/obvious questions.
    The main questions are:
    What can I grow in a greenhouse that I can't grow in a tunnel (and vice versa)?
    What are the advantages/disadvantages of each?
    Am I correct in thinking I can put a tunnel directly onto a bed providing I anchor it somehow but would need a more solid base for a greenhouse?
    Tunnels seem to have a darker/opaque covering whilst greenhouses are clear. Why the difference?
    I know there are a few questions but hopefully someone has the time to answer.
    Thanks

  2. #2
    veggiechicken's Avatar
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    Life's more exciting with seeds
    @realveggiechicken

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    Lymmguineas is offline Germinator
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    Quote Originally Posted by veggiechicken View Post
    Thanks Veggiechicken,
    That’s helpful. I did look to see if someone else had asked but must have missed that post.
    It certainly answers some of my questions but not all of them. I would still be interested in people’s views.
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    I think I've asked the same question myself - can't find it though.
    What is your plot like for security and vandalism? That would be my concern if I was spending big money on a GH or PT.
    Life's more exciting with seeds
    @realveggiechicken

  5. #5
    Lymmguineas is offline Germinator
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    Quote Originally Posted by veggiechicken View Post
    I think I've asked the same question myself - can't find it though.
    What is your plot like for security and vandalism? That would be my concern if I was spending big money on a GH or PT.
    Security is quite good to be honest.
    We’ve got padlocked gates which have the combination changed periodically.
    There were issues with vandalism a few years back but it’s been ok since we had the gates installed.
    The plot next to mine had a 12‘ by 8’ greenhouse installed last year and it’s been untouched by thieves and vandals. That plot had a paved area at the front so was relatively easy to install a greenhouse there.
    My plot is almost all cultivated so would present a different challenge if I wanted a greenhouse. I’ve got one “solid” space which currently has a derelict 6’ by 4’ greenhouse. The frame is bent, there’s no glazing and the door’s missing. It’s probably not worth renovating as I want something bigger anyway.
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  6. #6
    Squingy is offline Seedling
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    Hi Lymmguineas
    By greenhouse I assume you mean a glass paned greenhouse?

    What can I grow in a greenhouse that I can't grow in a tunnel (and vice versa)?
    To my knowledge it's no difference, but polys can plant in beds and dig into the earth easily, not sure abt gh. Can grow more stuff in poly, probably

    What are the advantages/disadvantages of each?
    GH, if one pane breaks, airflow is disrupted and the other panes follow soon. If you're not on top of it you're stuck with a a pileful of glass which is downright dangerous. Not sure how you source and fit the broken pane but even maintenance wise could be more expensive. They're really attractive though and sturdier than polys
    Polys aren't that dangerous, can put up and down. Low maintenance, just patch up if get a hole, rebuy a cover to fit the frame if tearings really bad. Cover needs replacing, maybe 3-5yrs maybe longer if not too windy. Major disadvantage in wind, may need to remove cover in winter to protect from winds.

    Am I correct in thinking I can put a tunnel directly onto a bed providing I anchor it somehow but would need a more solid base for a greenhouse?
    Correct, somewhat.
    The trick with a poly is, don't just anchor, BURY it. Bury the metal base all around, tuck the cover in and bury that too. Don't let any wind go up from under the cover - it'll blow away. Hard work in the beginning but believe me, worth it. Polys can go on slight slope. Usually bigger, higher than gh so more room to move.
    GHs I've seen were all on on solid base but maybe u could put on earth and use ground anchors to the frames? If not, with the gh you will lose all earth space on ground for growing. If you can ground anchor the GH are you going to be digging in there and are u spatially challenged like me and might shove a spade through a pane in the smaller space?

    Tunnels seem to have a darker/opaque covering whilst greenhouses are clear. Why the difference?
    Shading. Seed packs say full sun, my experience says some plants, like cucumbers actually don't do too well in direct, bright sunlight like we were getting and need some light shading. Yes, I know nobody ever says that. It's not a major issue really.

    If I may, think about the wind. Very strong winds get a GH, it will rip your poly or blow it away completely. Unless you are getting a Keder polytunnel ***drool***. In a sheltered spot on a rented allotment site I'd definitely do poly. Unless I was trying to win a pretty plot contest or impress someone.

  7. #7
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    When you say polytunnel, are you considering the cheaper kit types you can pick up on Ebay (typically green, sometimes referred to on this forum as a 'blowaway') or a small commercial quality one from a dedicated polytunnel supplier?
    He-Pep!

  8. #8
    Lymmguineas is offline Germinator
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    Quote Originally Posted by Squingy View Post
    Hi Lymmguineas
    By greenhouse I assume you mean a glass paned greenhouse?

    What can I grow in a greenhouse that I can't grow in a tunnel (and vice versa)?
    To my knowledge it's no difference, but polys can plant in beds and dig into the earth easily, not sure abt gh. Can grow more stuff in poly, probably

    What are the advantages/disadvantages of each?
    GH, if one pane breaks, airflow is disrupted and the other panes follow soon. If you're not on top of it you're stuck with a a pileful of glass which is downright dangerous. Not sure how you source and fit the broken pane but even maintenance wise could be more expensive. They're really attractive though and sturdier than polys
    Polys aren't that dangerous, can put up and down. Low maintenance, just patch up if get a hole, rebuy a cover to fit the frame if tearings really bad. Cover needs replacing, maybe 3-5yrs maybe longer if not too windy. Major disadvantage in wind, may need to remove cover in winter to protect from winds.

    Am I correct in thinking I can put a tunnel directly onto a bed providing I anchor it somehow but would need a more solid base for a greenhouse?
    Correct, somewhat.
    The trick with a poly is, don't just anchor, BURY it. Bury the metal base all around, tuck the cover in and bury that too. Don't let any wind go up from under the cover - it'll blow away. Hard work in the beginning but believe me, worth it. Polys can go on slight slope. Usually bigger, higher than gh so more room to move.
    GHs I've seen were all on on solid base but maybe u could put on earth and use ground anchors to the frames? If not, with the gh you will lose all earth space on ground for growing. If you can ground anchor the GH are you going to be digging in there and are u spatially challenged like me and might shove a spade through a pane in the smaller space?

    Tunnels seem to have a darker/opaque covering whilst greenhouses are clear. Why the difference?
    Shading. Seed packs say full sun, my experience says some plants, like cucumbers actually don't do too well in direct, bright sunlight like we were getting and need some light shading. Yes, I know nobody ever says that. It's not a major issue really.

    If I may, think about the wind. Very strong winds get a GH, it will rip your poly or blow it away completely. Unless you are getting a Keder polytunnel ***drool***. In a sheltered spot on a rented allotment site I'd definitely do poly. Unless I was trying to win a pretty plot contest or impress someone.
    That's fantastic. Thanks very much for the info/advice.

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