A popular Tree-Hugger article boldly claims that you can “build an underground greenhouse for $300.” While that is certainly possible if you do all the work yourself, and find free materials, more realistic budgets are far higher. The article does not say where it procured its $300 budget; likely it is from the original Walipini project, which was built using volunteer labor and recycled materials in a developing country. It also assumes you are doing all of the excavation yourself, making it only applies to those who own a backhoe or have a spare few months of their life to dig a large pit by hand. Building a durable underground greenhouse in a North American climate can be a significant endeavor, often costing a few thousand dollars. Whatever your budget, is important consider this and set realistic expectations so you are not surprised by costs down the road.
Another surprise for first-time growers is that building underground is not cheaper; often, it is more expensive than a standard greenhouse. To create the same durable and energy-efficient greenhouse that exists above ground, one must do all the same work, but in addition, excavate the site, remove a good deal of soil, and build sturdier walls that can resist the downward pressure of soils, and install drainage systems. That does not make the work unjustifiable. For their energy-efficiency, and stable year-round temperatures, underground greenhouses like Walipinis can definitely be worth it. But, do not opt for a pit greenhouse solely to cut costs.
A Walipini, or any underground greenhouse, can extend the season using a free natural resource. While an excellent strategy for many growers, one must carefully consider how to customize the design or building method to work for the local climate. There is a great deal of misinformation about Walipinis, but there are also some excellent resources to help you build a durable, long-lasting, and abundant underground greenhouse.
(original article found here)