homesteading · preparedness · self-reliance

Heating the Backwoods Greenhouse

winter storm 12-27-14 013This is April!? The weather in the U.S. has been less than desirable for the beginning of growing season. We live in the backwoods of Michigan’s upper peninsula, between Lake Superior and Lake Michigan.  Last night we received 8 inches of heavy wet, white stuff with a low temperature of 9 degrees. The day before it snowed all day leaving us with an additional 4 inches, a foot total in the last two days and it isn’t over yet! I lust for green but all I see is white!

Our beautiful woodland forests only see leaves on the trees for 4 months out of the 12 so when we set out to plant a garden, ya gotta make it quick! To get a jump start, we put up a clear, polycarbonate structure we refer to as the greenhouse. In the picture above, the red structure to the left is the chicken house and the mound leaning against the greenhouse is a pile of cut and split firewood. As you can see, there is a need for heat in this building. I’m about to should you how we do it.

The greenhouse sits on top of 3 full dump truck loads of road gravel to level out a slight downward slope.  The polycarbonate greenhouse is 16ft. x 20ft., trust me when I say we should have gotten a bigger one, however, it was all we could afford at the time. So how to heat this thing now that we had used up all our cash reserves? Propane and electric were simply out of the question as being too costly. Same with buying a woodstove, just didn’t have the cash.

I had purchased a book back around the year 2000 called “Solviva.”  How to Grow $500,000 on One Acre & Peace on Earth written by a lady named Anna Edey. The book describes Anna’s sacred vision and commitment to live sustainably and in harmony with life on Earth. Since 1976 she has made one astonishing discovery after another, which she had been developing under the name of Solviva Solar-Dynamic, Bio-Benign Design. The results of her experiments and methods have again and again exceeded highest hopes and expectations. I highly recommend finding a copy of her work and falling in love with Bio-Benign Design, as I did.

To make a long story not so long, I stole one of her designs, modified it to fit my needs and came up with a heat source for my backwoods greenhouse that Hubby built for me. It goes something like this;

We found an empty 55 gallon metal barrel and cut it in half, long ways. Maybe a little less that half is ok too. Dug a hole in the dirt floor of the greenhouse slightly larger than the half barrel and as deep, minus about two inches.

Greenhouse stove 010
Place a half 55 gallon barrel in the hole

Then we put the barrel in the hole and back fill leaving about two inches above ground. The reason I left the two inches sticking out with this one, is because in the spring my greenhouse has a tendency to flood with melting snow. The barrel filled with water and put out my fire one year, lesson learned!

Now, we lined the sharp barrel edges with angle iron cut to fit. Then add two across as supporting braces. Next lined the angle iron with woodstove gasket to seal up air leaks when theres a fire in it.

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Add two pieces of angle iron and gasket

Then next part is a little trickier. You need a piece of sheet metal at least a 1/4 inch thick, thicker is better but harder to work with. Your sheet metal should sit on top of the gasket material and cover the barrel. Measure back 18 inches and cut across the sheet metal. This will become the door to the woodstove for loading purposes. Hinges will make the door less hassle. Measure the chimney size and cut an appropriate opening in the opposite end.

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Cover with 1/4 sheet metal- hinges and chimney hole

Lay the sheet metal over the barrel and add the chimney and vent out the ceiling or side wall.

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Greenhouse woodstove 012

To be on the safe side, we made the chimney stick two feet into the air. Now let’s fire this baby up, eh?

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Start a fire

Ahhhhhh, success! But we’re not done yet. We need to keep a good moisture content in the greenhouse and hot air dries things out. I filled a 25 gallon barrel with water for the moisture part. As the stove heats the sheet metal plate under the barrel it heats the water too.

Greenhouse woodstove 003

Now we are ready to enjoy all that hard work. After a few days of heating up the stove, the floor will build up a warmth that radiates back into the room. I have also discovered, if I line the inside of the walls with 2 mill thick plastic, I get a warmer climate and less draft. The plastic is 3ft. wide and 25ft. long or whatever I happen to have on hand. Unroll the plastic so it runs the length of the side walls from the floor and tape or use magnets to hold it in place. Wrap around the whole inside of the greenhouse for extra warmth.

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About the time the out door temperatures stay above 40 degrees at night, remove the plastic if you want. You will need daytime ventilation and fans when the sun shines for sure as the greenhouse can heat up fast.

If you would like specifics or better details, feel free to leave a comment and I will answer your questions best I can or better yet I’ll get Hubby on it.


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