Growers are increasingly opting to grow cannabis in greenhouse structures according to a 2020 survey by Cannabis Business Times.  As of 2020, 41% of cannabis growers were growing in a greenhouse, up 7% from 2016. This trend is not surprising given the many benefits of growing in a greenhouse versus growing in a warehouse or outdoors.

Energy Savings

One of the biggest benefits of greenhouse growing is the savings in energy costs. Running grow lights for 18 hours a day in an indoor facility is very costly and not necessary in a greenhouse. Also, providing you have a quality greenhouse covering on your structure, you don’t have to worry about light spectrum and PAR in the same way you do with LED or HID lighting in an indoor facility. Nature takes care of it for you! Natural sunlight filtered through a light-diffusing greenhouse covering will ensure your plants are getting the optimum light for healthy growth.

Protection from Inclement Weather

In comparison to growing cannabis outdoors, a greenhouse provides protection from the elements: driving rain, wind, hail and extreme heat and cold events. In northern climates, a greenhouse also has the advantage of providing your plants with naturally warmer temperatures. Even on a cool day, if the sun is breaking through the clouds at all, the temperature in a greenhouse will rise by at least 20 degrees. Northerners also have a chance to extend the season with a greenhouse, compared to relying on Mother Nature alone.

Quality of Growth

Sean Dyament, owner of Indigenous Farms in Sault Saint Marie, Michigan has experience growing cannabis both in greenhouses and indoor warehouse-type environments. “You can get a bigger yield growing in a greenhouse and still produce tight, dense buds,” says Dyament, who has a passion for growing very large cannabis plants. His biggest yield so far in his greenhouse is nine pounds off of a single plant!

While the THC content and terpene profile are largely determined by the strain you’re growing, cannabis properly grown in a greenhouse will have the potency and terpene profile as that grown outdoors or indoors in a warehouse, according to many experts.

Dealing with Pests

As for pest control, there are advantages and disadvantages to whatever growing environment you provide. The ventilation in a greenhouse will likely be superior to that provided in an indoor facility, which will make it a little easier to control things like powdery mildew, which may be more of a problem in a converted warehouse. Healthier plants tend to do better at fending off disease and insect pressure. With that said, growing cannabis in a greenhouse can invite a number of different pests, according to Dyament, who uses an IPM (integrated pest management) approach to keeping pests in check.

Climate Control Tips

One of the challenges of growing in a greenhouse is keeping the greenhouse cool in the summer, especially in southern climates. If growing in a greenhouse in these environments, it’s imperative that the sides roll up for maximum ventilation and cooling. A fan and cooling pad system is an option for greenhouse growers. Natural ventilation is also an option, which is a method whereby the airflow is maximized by how a greenhouse is positioned in relation to prevailing winds and may include ventilation through louvers on the roof of the greenhouse.

Choosing the Best Greenhouse Covering for Growing Cannabis

One of the most important decisions any grower can make is to choose the right greenhouse covering. Experienced cannabis growers are impressed with the results they’ve gotten with Solexx™ greenhouse covering.

Developed in the late 1980s by a plant scientist, Solexx greenhouse film allows 100% diffuse light into a greenhouse. Diffuse light bends around corners, penetrating the canopy of the plant as well as the lower leaves and branches. This is particularly important in producing large buds with rich terpenes, which is the coveted goal of cannabis growers. Diffuse light also offers more growing space as there are no hot spots and shadows which can result in uneven plant growth and the need to move plants around. The twin-wall covering not only speeds plant growth but also reduces heating and cooling costs.

There are other benefits of Solexx coverings for growing cannabis. For instance, the film itself is translucent, offering a degree of security and privacy for cannabis growers. These coverings are very durable and often last past the 10-year warranty. In most cases, supplemental lighting isn’t necessary when growing cannabis in a greenhouse. However, many growers, including Dyament, use supplemental lighting for specific stages of growth, such as during the propagation of stem cuttings, aka cloning. Dyament also likes to use supplemental lighting on cloudy days to maximize growth and yield.

Installation of Solexx greenhouse coverings is pretty straightforward and is covered in this installation guide from Adapt8. If you can use a caulking gun and a drill to screw in the tap screws, you’re all set. Read more about Solexx.