Posted on

cannabis grow dehumidifier

Cannabis grow dehumidifier

Once the air is saturated with water vapor, the dew point is reached and water begins to condense on cooler surfaces, including on the plants and inside the buds. This condensation causes fungal pathogens to develop, leading to disease outbreaks.

Due to cannabis’ strict regulations, both for medicinal and commercial use, it’s necessary to eliminate disease without chemicals. In order to achieve this, growing spaces require dehumidification.

Cannabis is extremely sensitive to humidity. It’s susceptible to a variety of humidity related diseases such as botrytis, downy mildew and alternaria. Treating humidity in the growing space with a dehumidifier for cannabis is the most efficient method to eliminate diseases.

DryGair’s solution is designed for horticulture and is optimized for cannabis greenhouses and indoor grow operations. This allows DryGair to incorporate additional benefits for cultivation.

Do You Need a Dehumidifier for Cannabis Cultivation?

While many growers attempt to reduce humidity with the use of fans or cooling systems, such as HVAC, these methods fail to achieve the highest efficiency. This is due to these systems reducing humidity as a byproduct of their operation, rather than a dedicated, optimized condensation system.

Essentially, there are two ways to cool air in the grow room. Either you take the warm air out of the cultivation space and replace it with cooler air from outside, or use air conditioning. The first option is widespread among home growers. The basic condition for its proper functioning is that the temperature of air sucked in or blown into the grow room is not higher than the temperature you want in your cultivation area. For a very basic installation, it is enough to have a sufficiently strong exhaust fan.

Appropriate climatic conditions are essential on the road to a successful harvest – not only in regards to growing cannabis. However, maintaining these conditions is often a demanding task that both home growers and large producers need to solve. What happens most is that we have to cope with high temperatures and high relative humidity in our grow rooms. These two variables are closely linked and there are many ways to deal with them. In the following article we will examine them in greater detail.

Air humidity is tells us how much water is contained in a certain amount of air that surrounds us. Most of you are probably familiar with measuring the air humidity with percent. This is the relative or proportional humidity of air, which expresses the ratio between the actual amount of vapor in the air and the amount that the air could absorb under the same temperature and pressure. If it were fully saturated with water vapor, the relative humidity would be 100%. The second widely used identifier is the so called absolute air humidity. It expresses the weight of steam contained in a particular unit of air – in Europe, the weight of water vapor in grams per cubic meter of air is most often used.


As indicated in the previous paragraph, the reduction of relative air humidity can be achieved by raising the temperature in the grow room. This makes sense especially when the temperature drops significantly after turning the lights off – by more than 8 degrees Celsius. In this case, it is convenient to heat the room during the dark period and maintain the difference between day and night temperature at a maximum of 5–8 °C. The higher the difference between day and night temperature, the faster the plants grow.

The air conditioning needs to have required power to work properly. When purchasing an ordinary room air conditioner, it is enough to pick the cooling capacity according to the room size, or more precisely its volume. Normally, one cubic meter requires 30 watts of cooling capacity.

Air humidity

The dew point temperature is also important for growers. This term refers to the temperature when the air is fully saturated with water, i.e. when the relative humidity of the air is 100%, as we have mentioned above. When the surface temperature drops below the dew point, water vapor condenses into water.

Most dehumidifiers intended for indoor use are primarily designed to remove average air humidity at normal room temperature. This is not enough for your grow room. But even a weak dehumidifier is better than none, and any active dehumidifier from the supermarket will suffice when growing on one square meter. In combination with air conditioning, even these ordinary dehumidifiers can work well in medium-sized growing tents. Nonetheless if you want a truly reliable dehumidifier for a large grow room, pick one from a range of manufacturers that focus on dehumidifying areas used for growing plants or on dehumidifying industrial premises.

Cannabis grow dehumidifier

What’s more, air conditioners rarely run at night when the lights are off and there’s no additional heat added to the room. These are exactly the conditions that can allow mold and mildew to take hold. At East Coast Cultivation, Welch and his colleagues found it was better to oversize their dehumidifier setup with equipment that let them prepare for potential worst-case scenarios.

“When we do this calculation, it really is that simple,” said Retzlaff.

Strength in Numbers

“The single best tip for dialing in your humidity is to size your units properly and have dehumidifiers that work with automated controls,” said Welch.

One common misconception that leads to under-sizing a grow room dehumidifier setup is the idea that having an air conditioner means additional humidity control isn’t necessary. While air conditioners can remove some moisture, they are designed to cool, not remove water, and therefore don’t keep pace with the needs of a grow environment.

Perfecting Placement

“If you don’t invest in proper environmental controls, it’s almost negligent,” said Lee. “You’re setting yourself up for failure because controlling humidity is a key part of an integrated pest management strategy, and I include mildew and fungus as pests.”