Introduction
For long-term food security in cold climates, consider constructing a Walipini (underground greenhouse). This innovative structure allows for year-round food production without the need for artificial heating. By harnessing the natural warmth of the earth and sunlight, you can grow vegetables and herbs even in the coldest months. This guide will walk you through the process of building a Walipini, sourcing materials, and maintaining it for optimal food production.
Building the Structure
Step 1: Site Selection and Excavation
Choose a site that receives at least six hours of sunlight daily. Excavate a trench 6 to 8 feet deep and 10 feet wide. The length depends on your space and needs but typically ranges from 20 to 30 feet. Ensure the soil is compacted and level at the bottom.
Step 2: Constructing the Walls
Use sandbags to create a berm structure around the perimeter of the trench. This acts as both a wall and insulation. For a 10-foot-wide trench, you will need approximately 1000 sandbags, each weighing about 35 pounds. Place the sandbags tightly against each other to prevent gaps.
Step 3: Covering the Roof
Cover the roof with plastic sheeting. Use UV-resistant plastic to ensure longevity. The plastic should be stretched tightly over a wooden frame and secured with ropes or clips. The roof should slope at a 30-degree angle to the north to maximize sunlight absorption.
Step 4: Insulation and Ventilation
Insulate the walls and roof with straw bales or other insulating materials. This helps retain heat and prevents cold air from entering. Install vents at the top and bottom of the structure for proper air circulation. Vents should be covered with mesh to prevent pests from entering.
Sourcing Materials
Local Woodlands
For the wooden frame of the roof, source materials from local woodlands. Look for straight branches or small trees. You will need approximately 20-30 branches, each about 10 feet long. These branches will form the ribs of the roof structure.
Plastic Sheeting
Purchase UV-resistant plastic sheeting. You will need about 1000 square feet of plastic to cover the roof. Ensure the plastic is thick enough to withstand weather conditions and last several years.
Sandbags
Sandbags can be filled with local soil or sand. You will need approximately 1000 sandbags, each filled with about 35 pounds of material. This provides both the structural integrity and insulation needed for the walls.
Planting and Maintenance
Planting
Plant vegetables and herbs that thrive in cooler temperatures. Consider leafy greens like spinach, kale, and lettuce. Root vegetables such as carrots and beets can also be grown. Plant seeds in biodegradable pots filled with a mix of soil and compost. Place the pots on raised beds within the Walipini to ensure proper drainage.
Sprouting Seeds
Supplement your food production with sprouting seeds. These can be grown in small containers and provide a quick source of greens during the winter months. Common sprouting seeds include alfalfa, mung beans, and lentils. Soak the seeds in water for 8-12 hours, then rinse and drain them twice daily until they sprout.
Alternative Bread Production
For bread production without electricity, consider using alternative ovens. The Adobe Oven requires clay, cement, and a 30-gallon drum. Alternatively, a portable Dutch oven can be used over a fire. Store hard red wheat and grinding tools for flour production. You can also keep a supply of yeast and salt for leavening.
Summary
Building a Walipini is a practical way to ensure year-round food production in cold climates. By following these steps, you can create a sustainable and efficient greenhouse that requires minimal energy input. Supplement your garden with sprouting seeds and alternative bread-making methods to ensure a steady supply of nutritious food.