In this new series by Fullbloom, we are going to explore specifically the most important elements for a cannabis greenhouse, with a special focus on automation. Being cost-efficient is particularly important for growers, as the market matures and gets more competitive, resulting in prices going down. Thus, ensuring that your cannabis operation kicks off with the right foot is paramount in such a young and exciting industry.
Cannabis is often referred to as “weed” and, although it does grow like a weed, you’ll grow a poor quality product unless you take very good care of your cannabis plants throughout the cultivation (and curing) process. As the US cannabis market matures, so does the competition for high grade cannabis and doing so with minimal upfront costs and low ongoing overhead. In order to produce the highest quality cannabis in a greenhouse, it is crucial to use science and automation to ensure a successful cannabis operation.
There are many factors to consider when setting up a growing operation, from choosing the correct greenhouse for your property and needs, to what equipment and climate control options you choose to maintain an ideal environment. Whether you're planning a budget medical marijuana greenhouse, or a large commercial greenhouse, these are the essential factors to focus on.
Removing the risk of human error goes a long way towards having a successful cannabis harvest. There’s a lot of equipment that functions best when automated to work together, and there are some things that will still need the touch of a grower’s green thumb.
Climate control systems
Cannabis will produce a higher quality product if the plant doesn’t have to fight against big swings in temperature. An ideal growing environment maintains a temperature around low to mid 70℉ with a variance of no more than 20° in either direction. Additionally, too much humidity build-up can cause powdery mildew to form and break out. Thus, every good cannabis greenhouse should have an automation control computer and components to help maintain a uniform and ideal environment. The right automation suite will communicate between all of the equipment in your greenhouse to make sure it’s all working together to keep your plants healthy, and alert you if something goes wrong.
Heat and humidity build up is going to happen in every greenhouse, no matter your climate. It’s important to properly size your ventilation equipment to ensure a full air exchange at least once a minute. By using an adequate active exhaust fan on one end of the greenhouse and motorized louvers for passive air intake on the other end, you will create an active air exchange by bringing fresh air in to replace the exhausted hot and humid air. This creates a nice breeze for the plants and will actively cool the inside of the structure provided the outside is agreeable. This equipment can be automated through both temperature and humidity control points.
Passive air removal
One of the best methods to remove hot air and humidity, without running up your energy bill, is via automated ridge vents. An automated ridge vent will open up a section of your roof that runs the length of your greenhouse and allow hot and humid air (that rises) to escape out of the roof. Used in conjunction with sidewall roll ups, you can bring fresh air into your structure while the hot air is released. If the heat and/or humidity set points still climb too high, your ridge vent will close and the ventilation and any other methods you have for cooling will kick on until the ideal environmental setpoints are reached.
Greenhouse heating and insulation
Heating your Cannabis greenhouse is one of the easier things to do as greenhouses naturally retain heat during the day. However, at night time a standard greenhouse will not retain almost any heat as greenhouses typically do not come standard with insulation. At Fullbloom we like to insulate our Cannabis greenhouses by adding a second layer of poly and inflating the roof (and sometimes the sidewalls) to retain energy. Additionally, especially in severely cold climates, we include a foam board barrier that is installed 6-12” into the ground to break the frost line and create a thermal barrier and further raise the insulation value. Almost every cannabis grower in the mainland US will need dry burning propane or natural gas heaters to heat up the air zone, but there are additional options like hydronic and geothermal heating, which can increase the efficiency of where the heat goes.
Actively cooling a cannabis greenhouse is essential in almost any climate, when outside temps push past 90 even a well-ventilated greenhouse with ridge vents can get too hot. If you’re in a hot/arid climate evaporative cooling systems (wet walls) can be crucial to dropping temperatures. We’ve achieved temperature drops from 120 degrees to 70 at one of our Arizona facilities with the use of a proper-sized wet wall and ventilation package. High pressure fogging, shade cloth, and geothermal options can make a large difference as well. Understanding your humidity and heat range is crucial to determining what cooling systems to use, as you want to avoid raising humidity if you already live in a hot and humid climate.
Stay tuned for the second part of this series on cannabis greenhouses!