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What’s in a Greenhouse? Invest in Accessories to Improve Your Cool-Season Growing

ClearView Greenhouse So, you just bought a greenhouse. Now, how can you make those dreams of growing a lush, green paradise in the middle of winter come true? It’s easy. Just make sure you have all the accessories necessary to create the perfect environment for your plants.

What accessories? We’re glad you asked. There are many accessories you can buy to improve the growing environment for your plants. This two part guide will help you decide what to invest in this fall in order to get the most out of your greenhouse. This week we’re going to focus on covering and insulating your structure, and our next entry will focus on heating, ventilation and other important accessories for cool season growing.

Greenhouse Covering & Insulation

Whether you use film, polycarbonate or a combination of both, the covering on your greenhouse is the first line of defense against the outside climate, and you should consider your options carefully.

Greenhouse Film


Available in a variety of thicknesses and opacities, film can be a good choice for covering your greenhouse and is one of the least expensive options. Depending on the thickness, it can last up to four seasons before a replacement is needed. You can use a single layer or double layer with an inflation system. A single layer of film will provide the least amount of insulation and is best suited for milder climates. A double layer of film with an inflation system adds a pocket of air between the layers. Air is an excellent insulator, and if you plan on heating your greenhouse, this is the way to go.

 Air Inflation System for double layer film

Air Inflation System for double layer film

Light Transmission

Photosynthetically active radiation (PAR) light transmission is the amount of light the film allows to pass through it. It’s usually expressed as a percentage and varies from film to film depending on its properties. Clear film usually allows between 88 and 90 percent light transmission. Other types of film, including overwintering film, allow much less light transmission, and you should carefully consider the light requirements of the plants you are looking to grow before choosing a film.


Film that has anti-condensate properties prevents water from forming droplets within the greenhouse. It allows condensation to flow down the sides instead of dripping onto plants. Film without anti-condensate allows water to form droplets, which can lead to disease problems and reduced light transmission.


Film with thermal properties is ideal for heat retention. Infrared additives in this film provide superior light diffusion and will absorb and re-radiate infrared heat back down to the crop during the evening hours, saving as much as 30% on heating costs.


Twin Wall PolycarbonateRemarkably strong and lightweight, polycarbonate is a translucent, rigid plastic that is almost as transparent as glass. Polycarbonate panels are not the least-expensive option for covering a greenhouse, but they are longer lasting and offer greater protection against wind and snow.

Available in single layer or twin-wall, polycarbonate is light weight and easy to work with. The best option for cold weather growing is twin-wall polycarbonate, as it provides a pocket of air between the walls for insulation. Twin-wall polycarbonate comes in 4mm, 6mm or 10mm thicknesses; 10mm polycarbonate will hold up the best in extreme weather conditions and offers the best heat retention.


Properly insulating your greenhouse can drastically reduce heating costs and add an extra layer of protection from the elements. From adding insulation to installing weather stripping, there are many things you can do to help keep the cold at bay.

Clear Insulation

Adding a layer of clear bubble greenhouse insulation to the inside of your structure will help retain heat without reducing light transmission. Clear bubble insulation can even be helpful during the summer months by preventing overheating.

Installing bubble film

Weather Stripping and Spray Foam

Make sure your greenhouse is shielded from the outside with weather stripping and spray foam. These materials can be used to eliminate drafts in doorways, foundations and around ventilation systems.

Weather stripping

Climate Screens

Installing a heat retention screen can act like a blanket for your plants. These screens are usually installed on the rafters and can be manually or automatically controlled. Using the screen at night will help reduce heat loss, preventing wild swings in temperature and creating a more stable environment. A climate screen will also help prevent the formation of dew, reducing the risk of fungal diseases and mold. These screens can also be helpful in the summer months by providing shade.

Climate Screens


Using black/white reflective greenhouse flooring is a great, and often overlooked, method of maintaining an ideal environment for plants. With the white, reflective side facing up, heat and light will be evenly distributed throughout the greenhouse. The black side that is facing down inhibits weed growth and pests. It also seals out humidity caused by damp soil.

Greenhouse Flooring

Covering and insulating your greenhouse are the first steps to ensuring that you will be ready to grow when the cold weather arrives. Check back soon for part two where we will cover other accessories that will improve the growing environment for your plants during the cooler seasons of the year.

Greenhouse in winter

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