.
< All Topics
Print

Greenhouse

Photo by Mark Stebnicki: https://www.pexels.com/photo/field-of-plants-in-greenhouse-2886937/

What is a greenhouse?

Greenhouses are structures designed to create a controlled environment for growing plants. In arid regions like southern Africa, where water can be scarce and extreme temperatures are common, greenhouses offer several benefits. Let’s explore the main types of greenhouses and the advantages of having one in arid southern Africa:

Main Types of Greenhouses:

  1. Traditional Greenhouse: This is the classic greenhouse with a glass or plastic covering that allows sunlight to enter while trapping heat inside. It provides a stable and controlled environment for a variety of plants.
  2. High Tunnel or Hoop House: These are simpler and more affordable structures, typically made with metal hoops or PVC pipes covered with plastic. High tunnels are more basic than traditional greenhouses but still extend the growing season and offer some climate control.
  3. Shade House: In arid areas with intense sunlight and heat, shade houses provide protection by using shading materials like shade cloth to filter and reduce sunlight. They help prevent plant damage from excessive heat and sun exposure.

Benefits of Having a Greenhouse in Arid Southern Africa:

  1. Water Conservation: Greenhouses reduce water consumption because they have better control over irrigation. Water is used more efficiently as it can be targeted directly to the plants’ roots, reducing wastage.
  2. Extended Growing Season: Greenhouses create a microclimate that protects plants from extreme temperature fluctuations. This allows for an extended growing season, enabling year-round cultivation of various crops.
  3. Temperature Regulation: In arid regions, temperatures can soar during the day and drop drastically at night. Greenhouses help regulate temperatures, keeping them more stable, which is beneficial for sensitive plants.
  4. Protection from Harsh Weather: Greenhouses shield plants from strong winds, hail, and sandstorms that are common in arid environments. This protection reduces plant damage and ensures more consistent growth.
  5. Pest and Disease Control: By creating a barrier between plants and the outside environment, greenhouses can help minimize pest and disease infestations, leading to healthier crops.
  6. Better Crop Quality: With controlled conditions, greenhouse-grown crops often have higher quality, better color, and improved taste compared to crops grown in the open field.
  7. Year-Round Income: Greenhouses offer the opportunity for continuous production and consistent harvests throughout the year. This can lead to a more stable income for farmers, even during the dry season.
  8. Optimized Resource Use: Greenhouses allow farmers to optimize resource use, such as fertilizers and pesticides, leading to reduced costs and a more sustainable agricultural system.

Overall, having a greenhouse in arid southern Africa can be a game-changer for farmers and gardeners. It offers protection from harsh weather, better control over water usage, and the opportunity for year-round cultivation. By creating a suitable environment for plants, greenhouses increase agricultural productivity and promote food security in regions where water and climatic conditions can be challenging.

Water saving greenhouse

Conserving Water with Closed Greenhouses: A Game-Changer for Arid Regions

In arid regions like southern Africa, where water is scarce, agricultural practices must adapt to ensure sustainable and productive farming. One innovative solution is the implementation of closed greenhouses, which offer a remarkable approach to conserving water while enabling intensive greenhouse cultivation.

Understanding Closed Greenhouses:

Closed greenhouses, also known as semi-closed or controlled environment greenhouses, are designed with a unique feature that sets them apart from traditional greenhouses. They are constructed to minimize water loss, making them highly efficient in water management, especially in regions with low annual rainfall.

How Closed Greenhouses Work:

The concept of closed greenhouses revolves around maximizing the utilization of rainwater runoff from the greenhouse roof. In areas with limited precipitation, every drop of water becomes precious, and closed greenhouses excel at capturing and conserving rainwater.

The closed greenhouse system is equipped with a clever water collection and storage setup. Rainwater runoff from the roof is channeled into a series of water tanks with a combined capacity equivalent to the greenhouse’s water demand. In the case of our 300m2 greenhouse with a daily water requirement of 0.5L/m2, six 10m2 water tanks are needed to fulfill the water needs throughout the year with only rainwater.

Conserving Every Drop:

The closed greenhouse employs a comprehensive water management strategy. The collected rainwater is used judiciously to irrigate the crops, minimizing water wastage and optimizing water distribution to plants. This approach ensures that each drop of water is utilized effectively, contributing to a more sustainable and water-efficient agricultural system.

A Greener Future:

Closed greenhouses represent a sustainable approach to food production in water-stressed regions. By utilizing rainwater runoff as the primary water source, they reduce dependency on other water resources, such as boreholes or rivers, which are often overexploited in arid areas.

Promoting Intensive Greenhouse Cultivation:

In regions with only 200mm per year rainfall, where water resources are precious, the implementation of closed greenhouses allows for intensive greenhouse cultivation with reduced water requirements. The controlled environment within the greenhouse also provides optimal conditions for plant growth, leading to higher productivity and better crop quality.

Building Resilience:

Closed greenhouses not only help conserve water but also increase agricultural resilience to climate change. With unpredictable rainfall patterns and rising temperatures in arid regions, closed greenhouses offer a reliable solution to sustain crop production year-round.

A Step Towards Sustainability:

By adopting closed greenhouses, farmers and communities in arid regions can secure a sustainable supply of water for agriculture while minimizing their impact on the environment. These greenhouses present an opportunity for resource-efficient and climate-resilient farming, contributing to food security and environmental conservation.

In Conclusion:

Closed greenhouses stand as a beacon of hope in water-scarce regions, demonstrating how innovative approaches to water management can revolutionize agriculture. By capturing and conserving every drop of rainwater, these greenhouses offer a sustainable path to intensive greenhouse cultivation, ensuring a greener and more resilient future for farmers in arid southern Africa.

Heating without electricity

Heating a Greenhouse in the Semi-Arid Desert: Harnessing Nature’s Warmth Without Electricity

In the semi-arid desert, where the days can scorch under the sun but the nights turn bitterly cold, heating a greenhouse becomes a crucial challenge for farmers and gardeners. While electricity may not always be readily available, there are ingenious and sustainable methods to harness nature’s warmth and keep your greenhouse cozy throughout the chilly desert nights.

1. Compost Heaps and Chickens as Natural Heaters:

Embrace the wisdom of permaculture pioneer Bill Mollison and utilize compost heaps strategically placed in the corners of your greenhouse. Composting generates heat as organic matter decomposes. Positioning compost heaps in the corners will prevent cold air from seeping into the greenhouse, and their warmth will provide a nurturing environment for your plants.

Additionally, consider keeping chickens in the greenhouse during winter nights. Chickens are natural heaters, and their body heat can significantly contribute to maintaining a comfortable temperature inside the greenhouse. This approach offers a dual advantage, providing warmth and creating a symbiotic relationship where chickens help fertilize the soil with their droppings.

2. Water Barrels and Dark Stones as Thermal Masses:

Water has a remarkable ability to store and release heat. Incorporate large water barrels inside the greenhouse, positioned to absorb the sun’s heat during the day and release it as radiant warmth during the cooler nights. Dark-colored stones placed strategically around the greenhouse can also serve as thermal masses, absorbing heat during the day and radiating it back at night.

3. Aquaponics Tanks and High Carbon Soil as Heat Sinks:

If your greenhouse includes aquaponics tanks, you can utilize the water within as a heat sink. Aquaponics systems integrate fish and plants, and the water circulating in the tanks will retain heat, contributing to a warmer environment. Similarly, high carbon soil, like well-composted garden soil, can act as a heat sink, absorbing and storing heat during the day, then releasing it slowly at night.

4. Consider a Duck Pond or Natural Swimming Pool:

A large water storage system like a duck pond or a natural swimming pool can serve as an excellent heat storage reservoir for the greenhouse. During the day, the water absorbs and retains the sun’s warmth, helping maintain a temperate climate inside the greenhouse during the chilly desert nights.

5. Effective Insulation:

To maximize the benefits of the natural heating methods mentioned above, ensure your greenhouse has effective insulation. Cover the greenhouse with bubble wrap or other insulating materials, preventing heat loss and maintaining a stable temperature.

Conclusion:

Heating a greenhouse in the semi-arid desert without electricity requires resourcefulness and a deep understanding of nature’s principles. By implementing strategic placement of compost heaps, utilizing thermal masses like water barrels and dark stones, and incorporating living elements such as chickens and aquaponics systems, you can create a harmonious and sustainable ecosystem that keeps your greenhouse warm and thriving through the cold desert nights. Embrace these natural heating methods and showcase the power of nature’s warmth without relying on electricity in your semi-arid greenhouse oasis.

Managing Humidity and Heat in the Greenhouse without loosing water



We need to keep the Greenhouse closed – and NOT cool it with opening windows, if we want to preserve water, rather we need to cool it with adding shade where needed.

Explore using automatic window openers for moving shade louvers in place on a greenhouse, i.e when it is hot the device will move the shade in place, when it is cool it will move it away.

Looks like no-one is using mechanical window openers to move shading in place automatically – we can build something, patent it and sell it globally.

You could build mechanical automated shading systems so that our greenhouse gets shaded automatically when it gets hot. (Normally automated cooling systems automatically open windows but we don’t want to let out the humidity). You’ll find automated shading systems online but they are all inside the greenhouse – you need ours outside the greenhouse so you don’t get the energy in.

Worthwhile links

http://www.tunnelatunnels.co.za/greenhouse-tunnels-sales.htm

https://smartfarming.co.za

Article: DIY external greenhouse shading

Article: Top four ways of shading a Greenhouse

Article: Drip, Drip, Drip. Greenhouse Condensation

10 tips for recycling irrigation water in the Greenhouse

Article: Using shading for greenhouse temperature control.

Worthwhile videos

Simple cheap greenhouse build with outside shade solution

Table of Contents