There are two basic types of greenhouse misting. They are manual misting and automatic misting. The manual misting system is quite simplistic. The system is attached to a main source of water and is turned on and off as it is needed in the greenhouse. The operator manually adjusts the flow rate and the amount of time that is runs. The manual system is usually less expensive than an automatic system and may be a choice for a greenhouse on a tight budget. The automatic misting system works on a timer and may start immediately upon determining that the temperature or humidity has reached a specified level.