Build a $300 underground greenhouse for year-round gardening

Doc

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Interesting ...any of you guys ever try this? I'd think a few inches of snow would do in a plastic roof.

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Build a $300 underground greenhouse for year-round gardening

Growers in colder climates often utilize various approaches to extend the growing season or to give their crops a boost, whether it's coldframes, hoop houses or greenhouses.

Greenhouses are usually glazed structures, but are typically expensive to construct and heat throughout the winter. A much more affordable and effective alternative to glass greenhouses is the walipini (an Aymara Indian word for a "place of warmth"), also known as an underground or pit greenhouse. First developed over 20 years ago for the cold mountainous regions of South America, this method allows growers to maintain a productive garden year-round, even in the coldest of climates.

It's a pretty intriguing set-up that combines the principles of passive solar heating with earth-sheltered building. But how to make one? From American sustainable agriculture non-profit Benson Institute comes this enlightening manual on how a walipini works, and how to build it:

The Walipini utilizes nature’s resources to provide a warm, stable, well-lit environment for year-round vegetable production. Locating the growing area 6’- 8’ underground and capturing and storing daytime solar radiation are the most important principles in building a successful Walipini.

The Walipini, in simplest terms, is a rectangular hole in the ground 6 ‛ to 8’ 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 sun's rays to penetrate creating a warm, stable environment for plant growth.

This earth-sheltered greenhouse taps into the thermal mass of the earth, so that much less energy is needed to heat up the walipini's interior than an aboveground greenhouse. Of course, there are precautions to take in waterproofing, drainage and ventilating the walipini, while aligning it properly to the sun -- which the manual covers in detail.

Best of all, according to the Benson Institute, their 20-foot by 74-foot walipni field model out in La Paz cost around $250 to $300 only, thanks to the use of free labour provided by owners and neighbours, and the use of cheaper materials like plastic ultraviolet (UV) protective sheeting and PVC piping.

Cheap but effective, the underground greenhouse is a great way for growers to produce food year-round in colder climates. More over at the Benson Institute and the Pure Energy Systems Wiki.

Video at link: http://www.treehugger.com/green-architecture/build-underground-greenhouse-garden-year-round.html
 

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thunderdome

Member
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I am with you on the snow tearing up the plastic roof. Really like growing in a greenhouse but got too expensive to heat for hobby growing for me. Still use my glass house in early spring through Christmas. If we don't have a lot of temps in the low teens I have kept stuff in it year round. But if we have a week of temps in the teens and cloudy days look out everything will freeze and look like it is burnt. Sometimes it will come back though. If I was serious about growing food crop would have to heat so as not to take a chance.20130513_152229.jpg
 

bczoom

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Hey Thunderdome - been meaning to ask. Are you anywhere near Gainesville? I used to do a lot of work there. Is Lake Lanier's water level back up? I remember about 10 years ago it was so low that all the docks were basically on land.
 

thunderdome

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Hey bczoom, yes I am about 30 miles northeast of Gainesville. The lake levels are back up now but stayed down for at least a couple of years. The corp of engineers manage that lake and it seems that it is more important to generate power than to maintain decent lake levels. That along with some crazy laws that mandate so much water has to go on downstream into florida. There have been law suites and all kinds of fighting over the water in lake lanier. The government is involved so you know how that goes.:bonk:
 

jwstewar

Senior Member
Staff member
This sounds pretty neat and a good idea - in certain locations. Like others, I would be afraid of the snow on the plastic, but I think the bigger issue would be ground water. I know I've had holes open for various projects around here and with a matter of a couple days the hole may or may not be full of water. Most of the time I'm OK around here, but if we get a little bit of rain to raise the water table, guess where it is going?
 
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