Humidity

Humidity – Manage R.H. (Relative Humidity) in your grow room by adding a humidifier or dehumidifier to your climate control arsenal.

Humidity has an effect on plant transpiration (the evaporative process of water from plant leaf surfaces). If the air in your grow space is too humid, transpiration will be too slow, a plant growth will slow down. If the air is too dry, too much transpiration may occur however – plants will lose too much water through transpiration and the stomata will close.

Temperature also has an effect on transpiration – read up on VPD.

An R.H. of around 60% is generally accepted for plants during their vegetative phase and a lot of growers like to have their R.H. below 50% when their plants are in flower in an attempt to keep them free from molds.