In greenhouses, ensuring proper and controlled humidity levels is critical. A properly designed fog system can effectively accomplish this. Maintaining a constant relative humidity will reduce the plants demand for moisture and can maintain favorable growing conditions year round. Fog systems are an integral aspect to many nurseries and greenhouse propagation businesses.All air in a greenhouse contains a certain amount of moisture that is available to plant material at all times. Environmental conditions change the available water by heating, ventilation and solar effect. Plants (like humans) normally thrive within a comfort zone of humidity and temperature.