by Greg Green
Cannabis plants work best in the 40 – 80 percent relative humidity area. rH (relative humidity) is the amount of water in the air. Fresh air always is the best way to control humidity. If you have a rH measuring kit you can judge for yourself how much fresh air you need before hitting the optimum 60% level.
There are some expensive devices called De- humidifiers that control humidity in the room. This is not recommended unless you have a very large grow area underway. Just use fresh air and you can’t go wrong.