Humidifiers are incredibly useful to prevent a dry environment in your grow room: if you need to increase the moisture through the grow room, simply use a humidifier. Humidity will help determine your plants resilience against mould/mildew in addition to how much your plants need to drink, in fact, your plants will have a constant need to intake water, and the amount of water they need fluctuates with the humidity in your grow room. Since humidity changes how much water your plants drink, and the water you give your plants have nutrients in them, being in control of humidity gives you increased control over your plant's nutrient intake. The right humidity encourages strong, healthy, leafy plants with vigorous growth. Hydroponics offers many solutions from the simplest to the most economical and professional. Try them!