Electric blankets for a heating source for plants the gardern

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As I like to read about two years ago I was reading a book on raising houseplants. In it the author said he had bought the little heating pads to help get his plants started. He said that he got tired of having such a small area to have heat for his plants and tried an electric blanket under them and they did fine. He cautions as I do that the risk for electric blanket instead. I thought it was an idea that was worth trying I put one in a cold frame on the ground covered with plastic and raised plants in it into january and even had a few snows and it did fine.

My thought as I asked in my other thread is that if I covered the blanket with either peat moss or sand it would distribute the heat better and keep it more even. What I am thinking of doing is to build a small greenhouse about 8 1/2 ft x 12 ft. On each side put plant growing areas of about 2 1/2 to 3 ft wide and the length of the greenhouse and use two blankets for each area. I would put them on a layer of styerfoam (? Sp) thinking of using the 1 inch thick also I maybe having it made so that on really cold nights I could place side panels and put one on the top to make a kind of an insulated area that I think would create an micro environment that would allow many plants to live. I also think that the water bed warmer would be a better idea as it would be safer with the water involved. Any thoughts on this would be appreciated. I know that one big problem would be if the power was off for a long period of time.


-- gail missouri ozarks (gef123@hotmail.com), November 01, 2000


Hi Gail,

I have considered this as well, and thought the waterbed heaters would be good, since they are waterproof. Also, they are made to have something heavy lying on them, unlike blankets. The only trouble is, they are kind of small. Another alternative might be those electric mattress pads. They are made to have weight on them, but I suspect they're not waterproof. I would definitely use some plastic sheeting or other waterproof material over one of those. I've seen both of the above items go quite cheaply in the thrift stores.

-- Laura Jesnen (lauraj@seedlaw.com), November 02, 2000.

Maybe you've already done these things, but if not, reduce energy needs first. Here are suggestions:

Leanto model GH facing south and backed up against the house.Then, use a material like corrugated plastisc sheets( looks like clear plastic cardboard) like available from Farm Wholesale.We were impressed with them, including, not as much summer heat buildup, just as significant a problem for us.These two things cut down on how much extra heat is needed, in the first place.

Then,use fish tanks or large plastic containers in GH filled with water to collect solar energy.We used plastic green ones gotten on sale after Xmas,that were supposed to be for storing xmas stuff.Large & held up to the water pressure and cheaper than aquarium,and not breakable.

Finally you could use a electric livestock watertank heater in these tanks, for the few times you'd need extra heat.Safer and surely big enough. This is in KY so adjust the recommendations to your own part of the country.

-- sharon wt (wildflower@ekyol.com), November 02, 2000.

I have used waterpipe heater tapes in cold frames with great success. They are better than using waterbed heater as the electrical connections are designed for indoor/outdoor use. I ussually find them during spring (when I need them for planting head starts) at Wal Mart in thereduced rack for $3 to $5 ea.

-- Jay Blair (jayblair678@yahoo.com), November 03, 2000.

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