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Thread: Greenhouse Temperature Recommendation

  1. #1

    Default Greenhouse Temperature Recommendation

    What temperature does everybody keep their greenhouse at? I have my exhaust fan set to come on at about 95 or so and the thermostat for my heater is set at about 50. These temps seem to be OK so far, but I don't know if I should let it get warmer during the day (or cooler, for that matter). The main crops in the greenhouse are tomatoes and basil.

    This is my first year with a real greenhouse -- I've only had "Hillbilly Greenhouses" (hoop houses) in the past. Any other advice about maintaining greenhouses is welcome!


  2. #2
    Member Rick P's Avatar
    Join Date
    Feb 2007
    Palmer Alaska


    My exhaust fan is set to go on at 75, I don't heat. The minimum recommended air clearance rate for healthy plants is 3 minutes so the more the fan runs the better, IMO.
    BHA Member
    Bowyer to the forces of light in the land of the midnight sun.
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  3. #3
    Join Date
    Apr 2007
    Interior Alaska


    The standard rule for ventilation, absent any electrical fans, etc., is 25% of the sq. ft. area of the greenhouse should be available in openings for ventilation.

    I typically don't use fans when I have a greenhouse, but I cling fairly tightly to the 25% 'rule.'

    They also make hydraulic(?) jacks that are temperature actuated, require no electricity, and will open up vents to a 'limited' degree/span once they reach temperature 'x'.

    In the summer time, in the Interior, the sun is sometimes up many hours before I am, and so manually opening the greenhouse up before scorching temps strike doesn't always happen the way that I'd like it to.

    During those periods, I'll sometimes leave some of the vents open at night, knowing that I'm not likely to get up at 5:00 A.M. and race outside in my skibbies in order to open the vents.

    Ideally, I like my greenhouse to be between 80 and 95 degrees f. at the peak of the sun's arch. As it starts to cool, I'll close some of the vents.

    The hydraulic 'jacks' are best if you have a panel of plexiglass, poly, plastic, etc. framed into wood in the ceiling, and the jacks hooked up vertically to the sill of the panel and the roof framing, so that as the greenhouse heats up, the roof panel(s) raise (hinged near the roof ridge or peak), and ventilate more or less upward, which is the direction that the hot air wanted to go anyway. It's a win:win, and no electricity is required!! -AND- I get to sleep in some!!


  4. #4

    Default Now?

    Are you getting those 90+ temps. now, or are they coming later in the summer?


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