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Plastic grow houses - any experience?

Hello all! I'm thinking of buying a plastic grow house for next year - one which has stability pockets you fill with sand so it won't blow over - and having it on my decking against the back of the (south facing) house. I can't afford a proper greenhouse and don't really want my whole kitchen and living room to be taken over by seedlings again next year  :D  (I grow a LOT!)

Has anyone got any experience to share - do they work? Would I be ok to sow seeds under plastic propagators directly in the grow house?
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  • Allotment BoyAllotment Boy North London Posts: 4,534
    They do offer some extra protection, and you have already identified one issue in the problem with stability.  The other main issue is the covers only last 2 -3 seasons at best. If you can afford one a lean to which is glazed or at least uses rigid polycarbonate panels will last much longer and be better for your plants.  I have used them in the past but have switched. 
    AB Still learning

  • WibbleWibble Posts: 89
    I had one. The main problems I found were:

    1) because the plastic cover had green 'netting' through it, it didn't let as much light through. My garden doesn't get great light, so this might not be an issue for you with your south facing aspect.

    2) keeping it tethered to the ground! It blew straight up and over the fence more than once, no matter how I tried to weigh it down. It didn't have pockets like you're describing though (I sort of folded the bottom edge of the cover under some bricks), so again may not be an issue for you. 

    Happy growing!
  • I’ve got a small one which I’ve anchored by tying wire around the top just above the door and attaching that to the house wall. Then bricks in the bottom against the back legs.
  • AstroAstro Posts: 344
    I have a little plastic greenhouse and I've anchored it with wire, similar to the way @Mr. Vine Eye has. 
    It had a clear cover the first year but it became tatted so I replaced it with the green netted type which has held up better.

    It's handy for controlling conditions better than if the plants were left to the elements, and seedlings grow more quickly owing to the additional heat. The added bonus is because of the shelving it requires less floor space. 
  • Thanks all, this is very helpful. I think I'm going to take the plunge and give it a try. My plan is to invest in a proper greenhouse, it's just realistically going to take at least a couple of years to save for it. If this lasts that long and saves my kitchen / living room space it will be worth it! 
  • TopbirdTopbird Posts: 6,615
    edited December 2020
    They are better than no protection at all but instability is the major problem - particularly on sunny days when you need to open the 'door' to ventilate and wind can get in and under the cover. Tying to a secure fixing plus weighting is the best way to deal with it but not completely fail safe.

    Unfortunately if there's a really strong gust of wind you wouldn't be the first person to come home to find trays of precious seedlings all over the ground. 

    They also only offer a little bit of frost protection so best used as a growing on / hardening off cold frame or for propagating from cuttings. They are not really suitable for germinating seeds that require a minimum temperature above (say) 10C unless you wait until the night temps warm up.
    Heaven is ... sitting in the garden with a G&T and a cat while watching the sun go down
  • josusa47josusa47 Posts: 3,532
    My first one was the sort you can stand inside, with shelves either side.  Such small shelves, I filled it in no time.  The frame was constructed with so many small bits, the wind rocked it and it came apart.  All my hours of filling pots and sowing seeds in them wasted, spread on the ground.  The one I have now is all shelving, and a much better design,the components are bigger so it's more stable.  I've had two, maybe three years use out it.  When I dismantled it last year, some of the metal tubes were rusted into the plastic connectors and I couldn't get them apart.  So when I erected it this year, I applied vaseline to the tube ends.  I can endorse the problem with low light levels; I get some very leggy seedlings.
  • LiriodendronLiriodendron Scariff, County Clare, IrelandPosts: 7,201
    I haven't dismantled mine for the winter, because I've had to secure the frame through the cover to the shed behind it, using wire and vine eyes.  It's also cross-guyed (I used to be a Girl Guide in the good old days when we got taught useful things like knots...) which keeps it from inflating with the wind, and weighed down inside with concrete blocks.  It's been really useful this past year; non-sensitive seeds have germinated well in it, and it's also been good for growing on seedlings germinated in my heated propagator indoors.
    "The one who plants trees, knowing that he will never sit in their shade, has at least started to understand the meaning of life."  Rabindranath Tagore
  • AstroAstro Posts: 344
    Mine hasn't blown over in 2 years, when it's very windy I fasten the door, with lessening winds I open up a 1/4 or 1/2 depending. 

     I have fleece to pull over the plants if it gets cold. Sometimes if it's colder  I chuck a bit of carpet on the roof, if it's very cold I put a full blanket on it as well.  It isn't ideal but I'd struggle to grow as much without it.
  • BigladBiglad East LancashirePosts: 2,183
    I'm on my second but they're definitely a short-term solution. I've got mine well weighted and strapped to a fence.

    Currently housing a number of cuttings for the winter. I'll be happy with the investment if a few of them make it through until the spring.
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