Now this is something that differs from plant to plant but as a general rule of thumb, you need to know that when you increase the humidity levels in the air, you are basically telling your plant to absorb more water from the air than from the soil. Leaves have small openings called stomata and they open up and water is absorbed from there when the humidity levels are high. This also means that less water is going through the roots at this point in time. This is generally good for marijuana plants during the growth or the vegetative phase of their grow cycle. rnrnHowever, when your marijuana plant begins to enter the flowering stage, you as a grower need to know that this is the time that you will be providing the plant with nutrients which are required for flowering to take place in a better manner. These nutrients need to be provided by mixing them in water and the water being mixed into the soil which is where the roots will absorb it from. Hence, when you decrease the humidity levels using a dehumidifier during the flowering phase, the plant can actually pick up more water from the roots allowing all the nutrients to show their effect properly and for the flowers to bloom in the right manner! However, this is true for marijuana plants but different plants might have different needs.rn