Want to Enjoy Year-Round Gardening? Build This $300 Underground Greenhouse
Although it is never going to be a national sport, gardening does have many benefits, especially for the gardener. So much so that many people look forward to the gardening season and hate having to wait for the weather to catch up. But do they really need to wait?
There’s a sense of accomplishment and boost of self-esteem that comes from presenting fruits and vegetables grown by yours truly in your own garden. Some people garden to pay the bills, others garden to make their house look good, while many engage in this serene outdoor activity for its health benefits.
Whatever your reason for gardening, you’ll definitely benefit from having an enclosed, indoor space that protects your precious produce from the elements. Greenhouses are specially designed structures with walls and roofs made of transparent materials, such as glass, in which plants can produce fresh flowers, fruit, and vegetables all year round.
There are actually two types of greenhouses you can use. The first is a regular greenhouse, which simply acts as a season extender, extending your growing season for about two or three more weeks in the spring and fall. The second is the growing dome, a typically larger, stronger, and more regulated version of the regular greenhouse, which creates an enclosed, indoor garden allowing you to grow all year round. 
Many people erect greenhouses in their gardens. They are ideal for growing new seedlings later and earlier in the year, and protecting plants from the cold. However, building greenhouses can be very expensive, putting amateur gardeners and hobbyists off the idea.
Thankfully, gardening fanatics have a great alternative to try: a “walipini,” which allows them to grow fruits and veggies 365 days a year, yes, even through the winter. When growing in colder climates, gardeners often have to utilize various techniques to extend their growing time frame. This includes erecting hoop houses, cold frames, or greenhouses to protect their crops.
Creating a Patch of Warmth in Any Weather
Walipini, an Aymaran Indian word meaning “a place of warmth,” is also known as an underground or pit greenhouse. This type of greenhouse was first developed in the mountainous areas of South America, which experiences cold weather year-round as a result of the altitude. The walipini allows growers to maintain a garden that produces year-round, even in the coldest places. 
It combines the principles of an earth-sheltered building with passive solar heating, taking advantage of the core elements of both. The earth-sheltered building, in this case, is basically a dugout and you can easily build one of your own. Benson Institute, an American sustainable agriculture non-profit created this manual on how a walipini works, and how to make one.
Building the 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.
The manual also includes a visual aid which shows how to position and build a walipini. It also emphasizes on locating the growing area 6’ to 8’ underground and aligning it properly to the sun as this helps capture and store daytime solar radiation.
Utilizing Natural Heating Sources
With the combined thermal energy from the earth and the sun, much less energy is needed to heat up the inside of the walipini than an average above-ground greenhouse. Depending on your land types and location, you may have to take precautions in ventilating, waterproofing, and draining the walipini. 
The walipini is not just useful; it is also cost-effective. For instance, an average 20-foot by 74-foot walipini greenhouse costs around $300 to build. This cheap but effective underground greenhouse is the perfect solution for growers who want to produce food year-round, no matter where they are in the world.