Growing plants year-round, especially in cooler or variable climates, can be challenging. However, an underground greenhouse, also known as a “walipini” or “pit greenhouse”, offers a sustainable solution. By utilizing the earth’s natural insulation, these greenhouses provide more consistent temperatures, protect plants from harsh weather conditions, and extend the growing season.
1. Advantages of an Underground Greenhouse:
- Thermal stability : Earth has natural insulating properties. Even a few meters below the surface, the ground maintains a relatively stable temperature.
- Protection from the elements : Underground greenhouses are less exposed to wind, snow and hail, reducing the risk of damage.
- Extended growing season : The stable environment allows cultivation even in cooler months.
- Sustainability : Requires less energy for heating due to natural insulation.
2. Choose the right location:
- Sunlight : Find a location with maximum sunlight. South-facing locations are ideal in the Northern Hemisphere, and north-facing locations are ideal in the Southern Hemisphere.
- Water Drainage : Ensure the site has good drainage to prevent water accumulation. Consider raised beds or gravel paths to facilitate drainage.
- Accessibility : Choose a location that is easily accessible all year round.
3. Construction of the underground greenhouse:
A. Excavation:
- Depth : Dig about 8 to 10 feet deep to take advantage of the soil’s insulation. Depth may vary depending on your region’s frost line.
- Width and length : As required. A standard size might be 10×20 feet, but adjust if necessary.
B. Walls:
- Build walls out of bricks, stones, or earth bags. Reinforce with concrete if necessary.
- Insulate the north wall to retain heat. You can use straw bales, foam insulation, or other insulating materials.
C. Roof covering:
- Use UV-resistant greenhouse plastic, polycarbonate sheets or glass for roofing.
- Make sure the roof is sloped to allow maximum sunlight and allow rain and snow to drain away.
D. Flooring:
- A gravel base can improve drainage. Optionally, you can use concrete or even keep a natural flooring base depending on your preference.
e. Ventilation:
- Install vents or windows on the roof or at the top of the sloping roof to allow hot air to escape.
- Consider adding a door at each end of the greenhouse to ensure air circulation and accessibility.
4. Underground Greenhouse Maintenance:
- Monitoring : Check temperature and humidity regularly. Consider installing a thermostat.
- Pest Control : Due to its unique design, an underground greenhouse may be more susceptible to certain pests. Check regularly and use natural repellents.
- Watering : Adjust your watering schedule based on the plants and humidity. Remember that overwatering can cause drainage problems.
5. Additional Tips:
- Water Barrels : Place water barrels in the greenhouse. They absorb heat during the day and release it at night, stabilizing temperatures.
- Raised beds : Using raised beds can prevent waterlogging and root rot.
- Reflective surfaces : Place reflective materials on walls to maximize light distribution.
Diploma:
An underground greenhouse can be a fantastic and sustainable way to grow plants all year round. Although it requires some initial effort and investment, it’s worth the effort to get fresh, home-grown produce even in the colder months. Remember to maintain and inspect your greenhouse regularly to ensure the best growing conditions for your plants.