Choosing The Right Greenhouse Materials
Choosing the right greenhouse materials for your needs is key to having a successful garden. Whether you have a small greenhouse used for just a few plants or an entire enclosed vegetable garden using a large structure, the material does not differ much. Though it may seem like a large and daunting project, the correct information and guidance regarding what materials to purchase can help ease those fears. So, let’s go through and talk about the different types of structures, their coverings, and then some tips for light and heat efficiency.
The design and materials of a greenhouse structure can significantly impact its productivity and efficiency. The basic structure of a greenhouse includes rafters, end walls, side posts, sidewalls, and purlins (the horizontal beams to the rafters). The components make three types of greenhouses: detached, lean-to, and gutter. Each of these structures can be used for personal or commercial use. However, some may be better suited than others for your needs. Typically, lean-to greenhouses are attached to a home or other structure, making them more common for smaller, personal gardens. Detached greenhouse structures can be placed almost anywhere and can be configured in virtually any size, making them ideal for commercial growers but still very usable for commercial and non-commercial (residential) growers alike. Commercial growers most commonly use gutter-connected greenhouses. Gutter-connected is the term used for greenhouses that are connected.
The structure of a greenhouse, the flooring, and the greenhouse coverings can each be made out of a different combination of materials which plays a role in its effectiveness. Plants will only be as strong as their environment allows, so making sure that you have the right materials for your plants to thrive is essential.
The overall structure or skeleton of the greenhouse can be made from aluminum, galvanized steel, wood, or plastic, such as PVC. All the different greenhouse structure materials have different coverings and panels. Steel frames typically use polyethylene sheets or polyvinyl chloride (PVC) based fabrics.
Steel frame with plastic grow film tends to be the most common and cost-effective type of greenhouse. It also allows for multiple configurations and ease of repair.
Typically, the floor of a greenhouse consists of dirt, gravel, or concrete. The flooring material does affect the greenhouse’s heat efficiency and light transmission.
Dirt and gravel floors do not retain heat or protect plants from pests. However, it is an excellent choice for water drainage or ground planting. Concrete does retain heat, and porous concrete will allow for water drainage. However, it does eliminate the possibility of ground growing.
Glass, fiberglass, acrylic, polyethylene film, polyvinyl chloride, and polycarbonate are common greenhouse coverings. The covering is the most important aspect of the greenhouse. This is because it directly controls how much light your plants will receive.
Different materials are made to precisely control the light allowed to pass through, offering varying diffusion. Some materials completely block out all sunlight used to grow specific crops. Exercise caution when deciding which material is suitable for you because too much sunlight overheats plants, while too much shade can cause plants to die from an energy deficiency.
Polyethylene film is inexpensive, lightweight, easy to patch and repair, and can conform to any structure, making it very easy to use. That leads to why polyethylene is one of the most commonly used greenhouse coverings. Oxygen and carbon dioxide can pass through this greenhouse film because of its porous nature, allowing the plants to breathe even in a tightly sealed greenhouse.
Poly plastic film is excellent for growers because you can customize the material with different coatings and build it in any configuration needed. A UV stabilizer can be used on the poly film to slow its degradation from the sun and decrease the yellowing effect. There is an anti-drip coating that will help to prevent excessive condensation. There is also poly glazing that will help to diffuse light. This allows growers to maximize space by ensuring that all plants receive sunlight.
Poly reduces heat loss by 30% to 40% compared to glass. That is a significant heat retention benefit. Most poly film ranges from an R-value of .87 to 1.7. Like polycarbonate, poly can come in multiple layers to bring additional durability and other benefits.
Customer Installation Using Jiggly Greenhouse® Apex Grow Film
Polycarbonate greenhouses are made from thick plastic, making them both cheaper and more versatile than the traditional glass greenhouse. Although it is a better material to use than glass in some ways, it still has its issues. These greenhouses are commonly built in both a single-wall and a double-walled configuration.
Single-walled polycarbonate coverings may be more durable and cost-effective than glass, but they still have some issues you should consider. First, the single-wall polycarbonate sheets do not diffuse light nor insulate heat very well. The R-value (the insulation value) of a single-wall polycarbonate covering is just .83. Simultaneously, horticultural glass holds an R-value of .93. Regarding light transmission, it is also inferior to glass. Roughly 94% to 96% of light passes through, while 97% to 98% of the light goes through horticultural glass. Single-wall polycarbonate is not ideal for growers because it is a flammable material making it difficult to insure.
Twin-Wall or Double-Wall
Twin-wall polycarbonate is better than single-wall polycarbonate in almost every way. Double-wall polycarbonate's r-value jumps to 1.42, making it better than single-pane. Twin-wall also diffuses light, but only 80% to 84% of light passes through the panels. Additionally, polycarbonate panels are known to cloud over time. This clouding is often referred to as yellowing. If you choose to use polycarbonate panels, you need to monitor this yellowing effect because it will greatly reduce light transmission (the light passing through to the plants) through the panels. Condensation can also be an additional issue for twin-wall polycarbonate, leading to plant disease and poor light retention and transmission.
Some Tips for Light and Heat Efficiency
The actual greenhouse may do most of the work. However, there are some additional ways you can increase the efficiency of your greenhouse. The color of your pots and planters can significantly affect the plants. Black planters are great for attracting and retaining heat in the roots of the plant, whereas colored planters are better in hot climates where you don’t want excess heat. Benches have the same properties in color, so consider that.
Whatever you choose to build your greenhouse out of, it will provide a shelter for sustainable cultivation all year round. This helps with fewer trips to the store, reducing costs and your carbon footprint. Even a small greenhouse can make a big difference.