Greenhouses create a controlled environment and enable the cultivation of plants that will not survive under normal external climatic conditions. A greenhouse is useful for growing nonnative plants that require specific temperature, soil and water conditions. Greenhouses are usually made of glass or plastic and are completely enclosed to conserve the heat. Since no rainwater can reach the plants and the soil and the extra heat causes the soil to dry more quickly, proper irrigation is vitally important for optimal yield. The easiest method of achieving this in smaller greenhouses is to use watering cans. However, it is a labor intensive, crude and impractical for larger greenhouses.
Seep hoses are water hoses buried up to 3 inches below the soil of the greenhouse. These hoses have numerous tiny perforations all along their length and release water slowly into the soil. It is an efficient method of irrigating the soil. It avoids wetting the leaves, which can happen with some other methods, and thus reduces the risk of mildew and mold on the leaves. Also, because the water goes straight down into the soil, this method encourages roots to develop downward in the search for water and establishes the plant more firmly into the soil.
Drip Irrigation Systems
Drip irrigation systems work on a principle similar to seep hoses. In this case, the water pipes lie along the surface of the soil instead of under it. The perforations in the pipes allow the water to be delivered slowly and steadily into the soil. The benefits achieved by the drip irrigation system are similar to those achieved by seep hoses.
Misters release a fine mist of water that dampen the soil without disturbing it. Misters humidify the greenhouse with tiny particles of water that then settle on the soil and moisten it. The main disadvantage with this method is that the mist also settles on the surfaces of leaves and branches. This dampness creates ideal conditions for the development of mold and mildew. Thus, when misters are used, plants in the greenhouse must be closely monitored to identify and quickly eliminate the development of any damp-related plant illnesses.
Sprinklers are suitable for large greenhouse where the watering requirements are higher. Sprinklers are usually mounted overhead and release sprays of water onto the plants and soil. Sprinklers can be automated to turn on and off at specific times and are especially useful when the gardener is going to be away for an extended period of time. It is difficult to closely monitor the delivery of water in the case of sprinklers, making this system unsuitable for greenhouses that house a number of plants with varied water requirements. Sprinklers also present the problem of water settling on leaves and causing rot, mold and mildew.