How Do Greenhouses Work?

What is the Purpose of a Greenhouse?

A greenhouse is a structure primarily made of transparent materials, such as glass or plastic, designed to cultivate plants by harnessing sunlight and creating a controlled and protected growing environment. The purpose of a greenhouse is to extend the growing season for plants, protect them from adverse weather conditions like frost, excessive heat, or strong winds, and provide an optimal environment for growth by regulating temperature, humidity, and light levels. They allow you to grow plants that may not otherwise grow well in your climate. Greenhouses are used for various purposes, including growing flowers, vegetables, fruits, and ornamental plants, as well as for research and experimentation in agriculture and botany. They are essential for commercial farming, allowing growers to produce crops year-round in regions with harsh climates or limited growing seasons.

Different types of greenhouses

Traditional/Even-Span Greenhouses are the most common type, characterized by a gable roof and straight sidewalls. They offer good space utilization and are suitable for a wide range of crops. However, ventilation options are more limited and they are susceptible to snow accumulation on the roof.

Quonset greenhouses have a semicircular shape, providing good wind resistance and snow shedding capabilities. They are often used in areas with harsh weather conditions. The main complaints with this style of greenhouse are less usable growing space compared to traditional designs and limited headroom near the sides.

Lean-To are attached to an existing structure, such as a house or a building, on one side. They are space-efficient and cost-effective, making them ideal for small gardens or limited spaces. Sunlight exposure may be limited depending on orientation and they may require modifications to the existing structure for proper attachment.

Dome-shaped structures offer excellent strength and stability, along with efficient use of space. They are popular for their aesthetic appeal and suitability for geodesic designs. However, their construction is more complex and there is limited headroom near the edges.

A-Frame structures have a triangular shape resembling the letter "A." They provide good ventilation and snow shedding capabilities, making them suitable for areas with heavy snowfall. They may have less usable growing space due to sloped sides and limited headroom near the edges.

Sawtooth greenhouses have a series of ridges and valleys along the roof, allowing for optimal light penetration and ventilation. They are commonly used in commercial operations. Construction is more complex and more materials are needed compared to traditional designs.

Greenhouses made primarily of glass provide maximum light transmission for optimal plant growth. They are often used for ornamental plants and high-value crops. They can be expensive and have less insulating properties

Plastic greenhouses utilize polyethylene or polycarbonate materials for covering. They are lightweight, cost-effective, and offer good insulation properties. The lifespan is more limited as they are susceptible to damage from UV rays and extreme weather conditions, and the materials are not sustainable.

How does a greenhouse work?

A greenhouse replicates and enhances the greenhouse effect through a process that involves trapping solar radiation within its enclosed space. Sunlight enters the greenhouse through transparent materials like glass or plastic. These materials allow short-wave solar radiation (mostly visible light) to pass through with relative ease. Once inside the greenhouse, the surfaces of the plants, soil, and other objects absorb the incoming solar radiation. This absorbed energy is then re-radiated as longer-wavelength infrared radiation (heat).

The greenhouse gases present within the greenhouse, such as carbon dioxide (CO2), water vapor (H2O), and methane (CH4), absorb a portion of this infrared radiation. These gases have molecules that can vibrate in resonance with the infrared radiation, trapping heat within the greenhouse.

As the greenhouse gases absorb infrared radiation, they re-emit a portion of it in all directions, including back towards the surfaces of the plants and structures inside the greenhouse. This process effectively traps heat energy within the enclosed space, creating a warmer environment than the surrounding air outside.

The enclosed space of the greenhouse allows for better regulation of temperature compared to the external environment. During the day, solar radiation heats up the greenhouse, and at night, the trapped heat keeps temperatures from dropping too low. Ventilation systems and other mechanisms can be used to manage temperature and humidity levels to create optimal growing conditions for plants.

What are greenhouses made of?

Greenhouses can be constructed from various materials, each with its own set of pros and cons. The choice of materials for a greenhouse depends on factors such as budget, climate, desired lifespan, aesthetic preferences, and intended use. Each material has its own advantages and disadvantages, and growers should carefully consider these factors when planning and constructing their greenhouse. Glass provides maximum light transmission for optimal plant growth. It is durable and long-lasting and aesthetically pleasing. Glass can be expensive to purchase and install., and fragile and prone to breakage. Glass also has limited insulation properties compared to other materials. Polycarbonate Panels offer good light transmission while diffusing sunlight to reduce glare. They are lightweight and impact-resistant with excellent insulation properties, retaining heat better than glass. It is not as clear as glass, which may reduce light quality slightly. Polycarbonate can yellow or become brittle over time with exposure to UV radiation and the initial cost may be higher than some other materials.

Acrylic Panels offer good light transmission with high clarity and they are lightweight and impact-resistant with better insulation properties than glass. However they can be susceptible to scratching and become brittle over time with exposure to UV radiation. Fiberglass Panels are lightweight and durable with good light transmission and diffused light properties. Plus they are resistant to corrosion and weathering. Fiberglass can yellow or become brittle over time with exposure to UV radiation and has a lower light transmission compared to glass or some plastics.

Metal Frames like aluminum or steel are strong and durable, resistant to rust and corrosion and lightweight and easy to assemble. However metal is a conductive material, which can lead to heat loss in colder climates and the initial cost may be higher than wooden frames. They also require insulation to prevent condensation and heat loss. Wood Frames offer a natural look and aesthetic appeal with good insulation properties and can be customized and easily modified. However, they are prone to rot, insect damage, and warping if not properly treated and require regular maintenance (painting, sealing) to prolong lifespan. The initial cost may be higher than metal frames.

What are the benefits of greenhouse gardening?

Greenhouses provide a controlled environment that extends the growing season by protecting plants from frost, cold temperatures, and adverse weather conditions. This allows for year-round cultivation of crops that may not thrive outdoors during certain times of the year, which makes them essential in short, cold growing climates like we have here in Massachusetts as they allow us to get a head start on long season crops and keep them protected later in the season. Greenhouses allow growers to create and maintain optimal growing conditions by regulating temperature, humidity, light levels, and ventilation. This controlled environment promotes healthy plant growth, reduces stress on plants, and minimizes the risk of pests and diseases.

With the ability to control environmental factors, greenhouse gardening often leads to higher crop yields and better quality produce compared to outdoor cultivation. Growers can optimize growing conditions to maximize productivity and harvests. Greenhouses provide a physical barrier that helps protect plants from pests, insects, and diseases. This reduces the need for chemical pesticides and fungicides, leading to healthier plants and safer produce.

Greenhouses can be designed with efficient irrigation systems that minimize water usage by delivering water directly to the plants' roots. Additionally, the enclosed environment reduces water loss through evaporation, leading to more efficient water use compared to outdoor gardening.

Greenhouses come in various sizes and designs, allowing growers to maximize space utilization and grow a wide range of crops in a relatively small area. Vertical gardening techniques can also be employed to further optimize space and increase production. Greenhouses offer flexibility in crop selection and cultivation methods, allowing growers to experiment with different plant varieties, growing techniques, and crop rotations. This versatility enables growers to adapt to changing market demands and consumer preferences.

Greenhouse gardening can be more environmentally sustainable than traditional outdoor farming practices. By minimizing the need for chemical inputs, reducing water usage, and optimizing resource utilization, greenhouse growers can reduce their environmental footprint and contribute to conservation efforts.

Looking for a high quality pre-made greenhouse in Massachusetts?

Hometown Structures offers the finest craftsmanship with custom designs in a wide variety of sizes perfect for the home gardener to give your plants the perfect climate to thrive in a protected environment, keep pests away from your plants, grow plants and food that don’t otherwise exist in your area/climate and extend your season with options including 8mm twin wall polycarbonate for optimal insulation, venting and windows. Every custom shed greenhouse comes with 50-Year LP Siding and 30-Year Collapse From Snow Warranty.

Tap here to visit their website to learn more and book a design consultation today.