Year-Round Gardening with a Walipini !
Growers dealing with cold weather conditions use numerous methods to prolong the growing season, or to boost their crops. Such methods include using hoop houses, cold frames, and of course, greenhouses.
Greenhouses are mostly glazed complexes, and are generally costly to build and heat all winter long. A more economical and efficient approach to glass greenhouses is the walipini (meaning “place of warmth” in an Aymara Indian), sometimes referred to a pit or underground greenhouse.
A walipini is a greenhouse below ground reliant on a clear covering (typically plastic). It remains warm by absorbing heat from the sun. The walipini stays operational by soaking up the earth’s thermal energy.
Initially developed over 20 years ago for South America’s cold mountainous regions, walipinis allow growers to sustain a productive garden all year long, even in rigid climates.
What’s extraordinary about the walipini is that it mixes both earth-sheltered construction and passive solar heating. It uses the sun’s energy for cooling and heating to develop something that is both affordable and functional. This is much more economical to run than a traditional greenhouse.
The walipini taps into the earth’s thermal mass, so that significantly less energy is required to heat up the interior than an above-ground greenhouse. However, there are provisions to make involving drainage, waterproofing and ventilating. The walipini must also be aligned properly against the sun, which the manual goes over in detail.
Read also: DIY Geodesic Dome Greenhouse
The non-profit agriculture organization, Benson Institute provides an informative guide on how a walipini operates, and how to assemble one:
“The Walipini, in simplest terms, is a rectangular hole in the ground 6 to 8 feet deep covered by plastic sheeting. 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 rammed earth at the back of the building and a much lower wall at the front provide the needed angle for the plastic sheet roof. This roof seals the hole, provides an insulating airspace between the two layers of plastic (a sheet on the top and another on the bottom of the roof/poles) and allows the suns rays to penetrate creating a warm, stable environment for plant growth. (…)
The Walipini utilizes nature’s resources to provide a warm, stable, well-lit environment for year-round vegetable production. Locating the growing area 6’ to 8’ underground and capturing and storing daytime solar radiation are the most important principles in building a successful Walipini.”
According to the Benson Institute, their La Paz-based walipni field model, which measures in at 20-foot by 74-foot, cost approximately $250 to $300, thanks to the contributions of free labor offered by neighbors and owners, as well as the use of inexpensive materials like PVC piping and plastic ultraviolet (UV) protective sheeting.
Economical and efficient, this underground greenhouse is a practical method for agriculturalists to produce food in colder climates year-round, drastically reducing grocery prices.