Misting systems of greenhouses supply and maintain adequate humidity, filter the air, neutralise odours and reduce dust pollution. Controlled, intermittent misting minimises the moisture lost by plants in the greenhouse while avoiding condensation on the leaves, preventing the growth of mould and fungus. However, continuous misting is a waste of water. This practice ultimately drains essential nutrients from the plants’ leaves and decreases the soil temperature, preventing proper root development.
Environmental factors such as the amount of shading, ventilation and daily weather variation during warmer seasons determine what level of moisture the greenhouse must achieve to maintain deal conditions. Preventing the plants from overheating in a greenhouse is as important as protecting them against frost damage; both quickly kill them. However, too much humidity results in rot and disease, so plants should be watered only as necessary.
Centrifugal force is used to feed an adjustable flow of water through a high-speed fan, producing a light mist. The water droplets evaporate immediately in the air. The natural circulation created by the fan prevents cool air from settling around the plants and warm air from being lost too quickly. This maintains consistent temperatures while spreading the mist evenly inside the greenhouse.
A high-pressure pump is connected to a spray nozzle that is specially designed to generate droplets of water small enough to evaporate quickly. Vertical risers lift the nozzles above the plants so that the water can evaporate without leaving residual moisture on plants and other surfaces. Some high-pressure systems require set up by a professional installation company ensuring that their complex filtration system, feed lines, distribution pipes and assorted fittings are connected properly.
Greenhouse misting system mechanisms monitor humidity and evaporation rate, working together with thermostats and timers in controlling the internal climate of the greenhouse. Many systems use two adjustable time clocks. The first is a 24-hour clock that turns the system off at night and on in the morning. The second is a timing clock that controls how long each cycle lasts, making the cycles adaptable to fluctuations in weather conditions.