Greenhouse ventilation

Discussion in 'Greenhouse Growing' started by Sheps, May 1, 2017.

  1. Sheps

    Sheps Keen Gardener

    Joined:
    Mar 30, 2017
    Messages:
    382
    Gender:
    Male
    Location:
    West Yorkshire
    Ratings:
    +1,102
    Hi everyone...in about 7wks I get my first greenhouse, a Hercules Trafalgar 6ft x 10ft, it comes with 3 roof vents and 2 louvre vents.

    But, from what I have read, the more ventilation you have the better it will be, so I was thinking of adding an extra louvre vent to the order, or maybe even a second door so I can have the front door open and covered with fly screen and then exit through the backdoor.

    So, which would be better for ventilation, a 3rd louvre vent or a 2nd door?
     
  2. johnny canoe

    johnny canoe Gardener

    Joined:
    Apr 28, 2017
    Messages:
    30
    Gender:
    Male
    Occupation:
    Prairie Horticulturalist
    Location:
    Calgary Alberta Canada
    Ratings:
    +145
    I have an 8ft x 8ft double door, two roof vents and one louvre vent. We get high winds coming down the Rock Mountains and I get good air flow. I would still put in another roof vent to help heat escape. I do shade the GH everyday during the hottest part of summer.

    I think it would depend on the location of your GH but adding another door can't do any harm and I like keeping one end of my GH totally open all summer.
     
    • Like Like x 1
    • JWK

      JWK Gardener Staff Member

      Joined:
      Jun 3, 2008
      Messages:
      30,688
      Gender:
      Male
      Location:
      Surrey
      Ratings:
      +45,645
      An extra door will proved better through-draft. Depends on your orientation and prevailing winds as well. You will sacrifice a bit of space for another door so a better and cheaper alternative (and what a few of us do in summer), just remove a few panes.
       
      • Like Like x 1
      • ricky101

        ricky101 Total Gardener

        Joined:
        Jun 15, 2016
        Messages:
        3,273
        Gender:
        Male
        Location:
        Sheffield
        Ratings:
        +4,184
        3+2 sounds good and if positioned with a little thought you should achieve good air flow.

        If you want to add a 3rd louvre ok, but another door ? probably quiet expensive.

        Are the vents and louvres using automatic openers ? a real necessity imho.

        A fly screen does help keep out the bugs still they still get in via all the other vents.

        In high summer you need to add some shading which will keep the temps down, just as important as ventilation.

        What are you intending to grow in there ?

        Using benches ? having slatted ones help the cool air get around the plants better.

        What end of the country are you ? (can you update your profile location box) as that can affect how much ventilation you need .

        Seven weeks sounds a long time to order a ghouse ?
         
        • Like Like x 1
        • CanadianLori

          CanadianLori Total Gardener

          Joined:
          Sep 20, 2015
          Messages:
          9,687
          Occupation:
          Battle Axe
          Location:
          Oakville, Ontario, Canada Zone 5A
          Ratings:
          +30,478
          I have a 6x8 (48 sf floor area) with one automatic vent. I just added a louvre on the opposite side from the vent. Tested it during our one nice day a few weeks ago and the air flow was quite impressive.

          I also have fans but they are to keep air moving inside, not for ventilation. And I think because of those, I have no problems with mildew etc.

          I would think an extra opening would be overkill. 3 vents and 2 louvres in 60 sf is lots. That would be triple what I have for those extra 12 sq of floor area. Really, lots! And yes, @JWK is correct - a door would take away lots of growing space.
           
          • Like Like x 1
          • Agree Agree x 1
          • Sheps

            Sheps Keen Gardener

            Joined:
            Mar 30, 2017
            Messages:
            382
            Gender:
            Male
            Location:
            West Yorkshire
            Ratings:
            +1,102
            Thanks for the advice, Johnny and JWK :blue thumb:

            Hi Ricky...all vents and louvres will be on automatic openers and I will be making some external shading, green mesh / shade fastened to wooden frames which I can throw up when needed.

            I intend to grow Tomatoes to start off with, and then maybe some Peppers and Cucumbers.

            One side of the ghouse will have some integral staging, the type on cantilevers that gives you loads of room underneath.

            I'm in West Yorkshire, so probably about smack bang in the middle of the UK.

            I ordered the ghouse in February, but delayed delivery until mid June, this gives me some time to sort out the chap for the base, which is being done mid May and start to collect all the bits and pieces that Ill be needing.

            If 3+2 sounds OK I might not bother with the 3rd louvre, I just thought an extra one would improve ventilation?
             
            • Like Like x 1
            • Sheps

              Sheps Keen Gardener

              Joined:
              Mar 30, 2017
              Messages:
              382
              Gender:
              Male
              Location:
              West Yorkshire
              Ratings:
              +1,102
              Thanks Lori...it sounds like 3 vents and 2 louvres is going to be adequate, I think you have just saved me £85 :biggrin:

              Thanks for the explanation re the sf floor area, it's starting to make sense now :blue thumb:
               
              • Like Like x 2
              • JWK

                JWK Gardener Staff Member

                Joined:
                Jun 3, 2008
                Messages:
                30,688
                Gender:
                Male
                Location:
                Surrey
                Ratings:
                +45,645
                Are you already growing your tomato , cucumber and pepper plants @Sheps ?
                 
                • Like Like x 1
                • ricky101

                  ricky101 Total Gardener

                  Joined:
                  Jun 15, 2016
                  Messages:
                  3,273
                  Gender:
                  Male
                  Location:
                  Sheffield
                  Ratings:
                  +4,184
                  Looking at the Hercules site seems they do not do a metal base plinth for it, unlike many others ?

                  Does tend to make installation a bit easier and add extra height to the eaves.

                  What kind of base are you having made, just a concrete ring for the frame to sit on, a dwarf wall or a full concrete base / flags ?

                  If doing a solid concrete base or pointed in flags, one thing I found handy was to have a shallow channel running down the middle so that any excess water and muck can be easily brushed away.
                   
                  • Like Like x 1
                  • shiney

                    shiney President, Grumpy Old Men's Club Staff Member

                    Joined:
                    Jul 3, 2006
                    Messages:
                    61,004
                    Gender:
                    Male
                    Occupation:
                    Retired - Last Century!!!
                    Location:
                    Herts/Essex border. Zone 8b
                    Ratings:
                    +117,311
                    If you're going to grow toms and cues then be aware of the relative positions of them. Cues prefer a damp and warm atmosphere and toms prefer a dryer and cooler atmosphere. So put the cues at the end of the greenhouse and the toms towards the door.

                    Definitely don't have a door both ends otherwise cues won't be happy, you will have less growing room (you can never get enough doesn't matter what size the greenhouse is :noidea:) and it will cost you more. The ventilation you have should be sufficient.
                     
                    • Like Like x 2
                    • Sheps

                      Sheps Keen Gardener

                      Joined:
                      Mar 30, 2017
                      Messages:
                      382
                      Gender:
                      Male
                      Location:
                      West Yorkshire
                      Ratings:
                      +1,102
                      Hi JWK...after thinking I'd be too late this year to grow Toms, my local garden center have told me to buy the plants in mid May and grow them on and then transplant them to the ghouse.

                      Hi Ricky...yes, there is no base plinth, but the Hercules Trafalgar is a High Eave ghouse, so it should be plenty high enough.

                      The base will be as below, using 600mm x 600mm x 50mm paving slabs

                      Greenhouse-Base-Final.jpg
                       
                      • Like Like x 1
                      • Sheps

                        Sheps Keen Gardener

                        Joined:
                        Mar 30, 2017
                        Messages:
                        382
                        Gender:
                        Male
                        Location:
                        West Yorkshire
                        Ratings:
                        +1,102
                        Thanks for the advice, Shiney...I have decided to scrap the extra door / extra louvre idea and stick with what the ghouse comes with.
                         
                        • Friendly Friendly x 1
                        • ricky101

                          ricky101 Total Gardener

                          Joined:
                          Jun 15, 2016
                          Messages:
                          3,273
                          Gender:
                          Male
                          Location:
                          Sheffield
                          Ratings:
                          +4,184
                          The base layout looks fine, provided they are laid onto a properly prepared area / sub base if the site is now just lawn or a soil plot.
                          Its going to be there for many years so it will settle if the sub base is not sound.

                          A bit concerned about your water buts being on the same flags, when full its a big weight that will probably settle the flag down after a year or two ..perhaps have those apart from the main base by a few inches so they don't spoil the effect if they do sink a bit.

                          If this helps, if I was putting up another ghouse I would have these 4 items to hand.
                          A 5mtr steel tape measure for checking the diagonals.
                          A pack of plastic spacer for packing where the greenhouse base meets the flags.
                          A set square 24" or bigger, bought or DIY to ensure the frame sections are square etc. and a reasonably long spirit level for checking its all vertical.
                           

                          Attached Files:

                          • Like Like x 2
                          • Sheps

                            Sheps Keen Gardener

                            Joined:
                            Mar 30, 2017
                            Messages:
                            382
                            Gender:
                            Male
                            Location:
                            West Yorkshire
                            Ratings:
                            +1,102
                            Thanks Ricky...the site of the ghouse is going to be leveled first as it's a lawn, then a hardcore base will be laid and compacted and then the ghouse base laid on top.

                            I like the idea of having the water butt bases slightly apart from the main base, I might even have a couple more flags laid, then I can have 3/4 water butts connected.

                            Once the base is down I'm not going to touch it for a month or so, then hopefully it will be rock solid for when the ghouse goes up.

                            Thanks for pictures of the kit, but I'm taking a big short cut and having a ghouse erector put it up for me, that way it should be done right first time.
                             
                            • Agree Agree x 1
                            • JWK

                              JWK Gardener Staff Member

                              Joined:
                              Jun 3, 2008
                              Messages:
                              30,688
                              Gender:
                              Male
                              Location:
                              Surrey
                              Ratings:
                              +45,645
                              It would be a shame to miss out. Have you got room for a few plants in a sunny indoor windowsill?
                               
                              • Like Like x 3
                              Loading...

                              Share This Page

                              1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
                                By continuing to use this site, you are consenting to our use of cookies.
                                Dismiss Notice