Inexpensive way to heat greenhouse?

Discussion in 'Gardening & Plant Propagation' started by kemrefarms, Nov 5, 2005.

  1. kemrefarms

    kemrefarms Head Weed Wrangler

    May 9, 2005
    Northern California
    I am looking for an inexpensive way to heat a greenouse, a small area about 10feet by 12 feet. Any suggestions or websites would be appreciated, thanks.
  2. pickapeppa

    pickapeppa Well-Known Member

    Jan 1, 2005
    Ours is 16 x 16 feet. Here's what we did one year to start seedlings in Feb/Mar in zone 5:

    Section off an area about 3x4 with plastic sheeting from ceiling to floor. Overlap at loose ends for your "door". In the center place an oil-filled radiator on bricks to keep it dry and plug it in. When the sun would shine, there was no need to run the heater as temps would stay above 75 degrees even in freezing temps. When it was cloudy, we ran it on low, when night time temperatures were below freezing we would run it on high. This kept the area inside within the range of 70 to 90 degrees. It worked like a charm. I don't think the electric cost went over $20 a month. Unfortunately, we don't have electric in our greenhouse yet so ran it on an extension cord. After the first couple of months, I smelled burning plastic and found the cord to the heater had warped. DH hasn't remembered to replace the plug end yet so . . . I'm focusing on greenhouse gardening without heat.

    Plants to mature in the fall and keep over winter: Anything in the brassica family (broccoli, broccoli raab, cauliflower, cabbage, pac choy), spinash, lettuces, celery, green onions, leeks, swiss chard, turnip greens, garlic, carrots, parsnips, cilantro, parsley, radishes, snap peas, peas, beets, turnips, kolrabi, kale. Some of these will eventually freeze when temps drop below freezing in the greenhouse (peas are a good one), but some of them are only damaged on the outer leaves which you then remove and use the rest of the produce as you need it, and some come through the winter unscathed.

    I love this system. It requires no added heat or light and when you get it worked out for your greenhouse, can deduct significantly from the grocery bill and add significantly to your health. There is nothing nicer than going into your toasty little greenhouse mid-winter and clipping something fresh, pesticide-free and healthy to have for dinner. And, spending a sunny warm afternoon pampering your little plants while it's frosty outside is just plain good for the soul.

    If your interested in finding out more, I would recommend the book:

    Four Season Harvest by Elliot Colemen

  3. JAK

    JAK Well-Known Member

    Oct 15, 2005
    New Brunswick
    In theory it is better to heat the beds from underneath than to heat the air. Even if you have small flats it would be better to set these on heated beds. Traditionally the hot beds would be fresh manure composting beneath the topsoil. You could also flake a 1" garden hose or flexible pipe in the bottom of each bed, and run hot water through it from your house if it is handy. If the house is not handy, set a large cistern right into the ground in the middle of the greenhouse and have the 1" garden hose begin and end in the bottom of this large cistern such that you can still lift at least one end of the hose out. When you need to add heat to you greenhouse, empty the cistern and heat the water up and refill the cistern up by running the hot water through the beds and into the cistern. You can carry hot water from your house, or have a small wood burner inside the greenhouse. There are also woodstoves for heating up hot tubs. You could also put a hot tub in your greenhouse. 10 imperial gallons of water heated to 210F will provide 15000 BTU of heat relative to 60F, and will require about 2-3 pounds of wood to be burned.

    It might be fun to think of your greenhouse as a model of the passive solar / wood heated home you might hope to own someday.
  4. bonnie lass

    bonnie lass Semper Fi

    Nov 3, 2004
    Beautiful Cape Cod
    Do a google search on "Solviva"