Usually, growing food in cold climates and extending growing seasons requires some type of greenhouse. The problem is that greenhouses – like glass ones – require a large investment, both to build them and to maintain crops during the winter.
A much more accessible and effective alternative is the walipini (an indigenous Aymara word that means “a warm place”), which is basically an underground greenhouse.
First developed twenty years ago for the cold mountainous regions of South America, this method allows farmers to maintain a productive garden year-round, even in the coldest climates.
Here you can see a video (in English) of a walipini that even incorporates some interior space for chickens and goats. The incredible thing about the walipini is that it combines the principles of passive solar heating with an earth-protected structure. The way to do it is very simple:
The walipini, in simple terms, is a rectangular hole in the ground two or three meters deep, covered with a blanket of ultraviolet plastic. The longest area of the rectangle faces the winter sun (to the North in the Southern Hemisphere and to the South in the Northern Hemisphere).
A thick wall of pressed earth at the back of the structure and a much smaller wall at the front provide the correct angle for the plastic roof. This roof seals the hole, provides an insulated air space within the two layers of plastic, and allows the sun’s rays to penetrate, creating a warm, stable environment for plant growth.
If you want to build your own walipini, here is a practical guide courtesy of the FAO. According to the Benson Institute, the cost of one of these underground greenhouses is $250 and up to $300, so there’s no excuse!