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Thread: Keeping your Greenhouse warm this winter

  1. #1
    Join Date
    Jan 2002
    Location
    Center Point, TX
    Posts
    256

    Keeping your Greenhouse warm this winter

    I have made this post also over at www.homesteadingtoday.com where I moderate the gardening and Plant Propagation Forum.

    I hate to bring up this subject as I will get tomatoes until late November or early December, but many of you will see frost before the end of September, and it is not too early for you to be thinking this direction.

    Heard of a really neat way to insulate a greenhouse. Many places recommend using double layers of plastic. It has been suggested that in really cold areas that you first put on the inside plastic layer and then in between the ribs of the greenhouse frame you attach long strips of the large bubble commercial bubble wrap. Then you put on the outside layer of plastic. I can see where this would do wonders for maintaining heat in the greenhouse. I sure wish I could remember wher I read it so I could give proper credit for the idea, and I think its a great idea.

    This year I will use double plastic on my greenhouse, but in South Central Texas I doubt I will need the extra bubble wrap insulation. I use regular clear landscaping plastic from Home Depot on my greenhouse as I need it as a greenhouse for only about 4-5 months a year and the other parts of the year it doubles as a shade house with shade cloth.

    Another post to follow on remote reading Greenhouse thermometers. I will probably just resurrect last years postings.
    Gary J
    Center Point, TX
    Hill Country Texas Master Gardener
    USDA Zone 7B
    AHS Heat Zone 8

  2. #2
    Join Date
    Feb 2002
    Location
    Surrey, BC, Canada
    Posts
    221

    bubble wrap

    Gary-what a great idea, I see it was a fellow in England that originally posted the idea.

    I have to price this bubble wrap, but it would eliminate the need to run the fan and make the double layers airtight, so that would be a plus. I am thinking of maybe "wrapping" my low tunnels this winter, since I will have some marginally hardy clematis potted up to get thru the cold bits. Be interesting to see how this helps with the heating bills, I'm sure it will pay for itself here.

    With a low tunnel, I'm wondering if I can make use of my bottom heating cables or if I'll need an additional fan/heater for cold snaps. Heat cable runs on 5 watts per foot, all of which is converted to heat, this should be more efficient than using light bulbs which can also work in areas that don't get too cold. Nice thing about cable is it distributes that wattage all over the place, instead of just concentrating it around one point, like a 100 watt light bulb.

    I'm trying to avoid really involved heating systems here, coz we rarely go below -7 C. (20 F.) and these clematis are actually hardy to that point in the ground. They will be more tender in pots tho, so I want to be on the safe side. Just keeping the cold, dry wind off them, and many other borderline things here (phormiums, hebes, the hardier fuchsias) and keeping them from being waterlogged during our wet coast winters will do wonders for a lot of things here. The actual cold temps are probably one of the least problems in my area. More stuff rots than freezes to death in the winters here.

    Anybody know where bubble wrap is cheap? I did see some for sale at home depot, not sure if that will be the best deal. Probably places that sell packing materials for businessses will tend to sell this stuff (?) Guess I'll have a look around here, we've got a few months yet--Glen in BC

  3. #3
    Join Date
    Jan 2002
    Posts
    443

    bubble wrap

    gary and glen wait till you price bubble wrap.hold onto your shorts you wont believe how expensive it is.and when it comes time to do a full size greenhouse .oh my ouch .i cant quote the price . here is another thought on it ! is it UV stabilized. if its not you will really be throwing away money.
    i like the stuff for insulation but i would use it in a short term way. here is a website you may want to check out , they have a product for covering GH's its not to cheap but may do what some people want and thats to insulate. they sent me samples of there products. its is a flexible twinwall.
    www.farmwholesale.com
    good luck i saw this product at the ohio florist show in columbus ohio in june .
    shepp

  4. #4
    Join Date
    Aug 2001
    Location
    Zone 9a - Gulf Coast
    Posts
    9,934

    Heater and Exhaust Fan Calculators

    Shepp and All,

    That is a very interesting and informative web site. I used their heater and exhaust fan calculators and decided to bookmark the site. I also requested a sample along with a catalog.


    Thanks for passing the information along to us!

    For those of you who have not yet taken the time to surf the Wholesale Farm Greenhouse web site, I encourage you to do so.

    Here are the specific links to their online calculator pages:

    Greenhouse Heater Calculator

    Greenhouse Exhaust Fan Calculator

    Enjoy!
    Ann B.
    Zone 9a
    Gulf Coast


  5. #5
    Join Date
    Jan 2002
    Posts
    443

    check out this outdoor woodburner company

    i use a outdoor woodburner to heat with . here is one that is very good . i think maybe better than the brand i use. for many reasons. one of them is its to small .
    check out this one www.centralboiler.com

  6. #6
    Join Date
    Aug 2001
    Location
    Zone 9a - Gulf Coast
    Posts
    9,934

    Bumping...

    Hi, Everyone!

    I am bumping this thread because there are so many threads on greenhouse heaters, and I thought this particular one might be useful to you as well...
    Ann B.
    Zone 9a
    Gulf Coast


  7. #7
    Join Date
    Aug 2001
    Location
    Zone 9a - Gulf Coast
    Posts
    9,934

    Greenhouse Heat Loss Factors

    The following link has a table of heat loss factors for various types of materials used to cover greenhouses. It will be helpful when computing what the heat requirements of your greenhouse will be.

    Table of Greenhouse Heat Loss Factors

    Hope That Helps!
    Ann B.
    Zone 9a
    Gulf Coast


  8. #8
    Join Date
    Aug 2001
    Location
    Zone 9a - Gulf Coast
    Posts
    9,934

    Greenhouse Heating Formula - Accounting for the Wind Factor

    This site has a formula which accounts for the 'Wind Factor'.


    Greenhouse Heating Requirements - Accounting for the Wind Factor
    Ann B.
    Zone 9a
    Gulf Coast


  9. #9

    If you guys will excuse a few remarks from the peanut gallery

    About the idea about the sandwiched plastic bubble cloth in between as an insulator, if it is too expensive,

    Why couldn't you

    put a third layer of regular plastic in between the sandwich and instead of using a fan to blow the plastic apart constantly, you could attach, possibly even with hot glue, some quarter round molding on alternate sides several feet apart (that stuff is not cheap either) so what about some privet whips, to sandwich air passively on either side of the inside and outside plastic.

    Is this confusing? All you need is something to hold the plastic apart, the air would most likely be there.

    I'm going to my room now! I don't know beans about greenhouses yet.
    Marguerite, GrannyGarden
    www.kirbyville.net
    www.tex-la.net

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