As of this writing, all recreational plants in Colorado and Washington must be tested for contaminants such as mold and bacteria (Colorado is currently working to require testing for medical marijuana as well). With the push behind legalization, there is also a push to ensure that the products consumers buy are safe for consumption. Gone are the days of people clamoring for any product they can find - legalization is turning people into savvy consumers.
With some testing labs reporting mold in as many as 80 percent of the samples they test, it is safe to say that mold growth is a large problem for indoor gardens. While there are many ways to combat mold growth when caught early enough, it is better to prevent the mold from growing in the first place.
Mold likes high temperatures (about 70 degrees and higher), high humidity, darkness and stagnant air. Unfortunately, this closely approximates the environment that is created during night cycles for many indoor Cannabis gardens.
During the day, while the lights are on, cooling is constantly being provided, keeping the air moving and the humidity levels under control. However, when the lights are off, so is the cooling system (most of the time) and thus, your humidity control. This results in humidity spikes and stagnant air, making night time cycles the most susceptible time for mold growth.
Mold especially loves damp environments, so keeping the humidity levels inside your garden at a constant level will go a long way towards preventing an outbreak within the canopy. Typically, dehumidification only takes place while the room is being cooled - dehumidification is actually a by-product of air conditioning. This means that if your garden isn’t being cooled when the lights are off, the humidity levels will spike to dangerous levels. An often overlooked factor, night-time dehumidification is crucial to preventing mold growth.
When looking for a climate control system, be sure to ask if it can provide 24-hour dehumidification, even when cooling is not taking place. If it doesn’t, keep looking.
Best practices such as a consistent humidity level and temperature control day and night can go a long way towards reducing the amount of mold found on your end product.