Air control is almost as important as cleanliness for pest prevention. Keeping the air at the right temperature and humidity and properly controlling air flow can make life for pests so difficult that they cannot successfully colonize your plants.
An ideal temperature and humidity for pest prevention in your grow room is between 68 and 75 degrees Fahrenheit and between 40% and 60% humidity. High humidity opens the door for molds, while low humidity encourages insects. Low humidity also makes the plants transpire more water, wasting both water and the plant’s energy.
It is important to note the relationship between temperature and humidity. As a quantity of air cools, its relative humidity increases. As a quantity of air heats up, its relative humidity decreases. This is because the amount of water that can be contained by a quantity of air increases with increasing temperature. Thus, some adjustments to grow room humidity can be made by manipulating the temperature of the air.
Air temperatures lower than about 60 degrees tend to raise humidity enough to cause concerns, and temperatures higher than about 85 degrees increase vigor in pests, making them reproduce faster. These temperatures (lower than 60 degrees, higher than 85 degrees) will inflict some stress on the plants, and can cause female plants to grow male flowers .
This is a video about setting up proper ventilation. This is very important for pest prevention.
Proper air flow and ventilation are extremely important for pest prevention in the garden. A vent fan should be used to remove air from the highest point of the grow room. Vent fans have a CFM (cubic feet per minute) rating that should be high enough to exchange the entire volume of the grow room air in 5 minutes.
New air should be taken in through filtered vents near the base of the plants in the garden. This will create an upward flow of air, which makes life extremely difficult for insects. An oscillating fan should be used in every garden to keep the air in the grow room turbulent, which also helps deter insects. Never use any pesticides on your marijuana plants.