A greenhouse is an enclosed structure made of glass or plastic that allows radiation from the sun to pass through but not vice versa. Simply put, it traps the heat from the sun in an enclose space. Since a greenhouse is a closed space, it's necessary to maintain the proper humidity and ventilation required for a plant's growth. Greenhouses are typically built of plastic or glass.
The cost of a greenhouse depends on various factors such as structure size, permanency of the structure and the type. According to the University of Arkansas Extension, greenhouses can be built for $2 per square foot with minimal heating and ventilation equipment, while greenhouses with best-in-class heating and ventilation equipment cost up to $4 per square foot. This cost includes flooring, heating equipment and structure building costs. This does not include the cost of the land, plants or maintenance.
There are certain factors on which the size of your greenhouse depends like available space, the selection of plants and headroom. Another important factor that determines the size of a greenhouse is the heating requirements. If only small shrubs and plants are to be planted in a greenhouse, there is no point in making the ceiling of the greenhouse 16 feet high and increase the heating requirements and associated costs. The size thus needs to be decided accordingly.
A greenhouse ideally should be located where it will receive maximum sunlight. If the greenhouse is going to be utilized throughout the year, make sure that the location receives sunlight in winter, too. Water drainage is another criteria. Always try and build a greenhouse above ground level so that drainage of rain water is facilitated naturally. Other criteria to be considered include easy availability of water and electricity. Access to the greenhouse should be convenient for the people using it.
Environmental systems include equipment that helps to maintain proper levels of heating, air circulation, cooling and ventilation. Heating requirements are based on the temperature requirements of the plants being grown. Air circulation is vital to maintain uniform temperature in the greenhouse and is achieved by installing circulation fans. Without air mixing, hot air settles at the top while cold air is at the bottom.
Irrigating a Greenhouse
Greenhouse plants can be watered manually with hand-held containers or sprinklers. Automatic watering systems are also available. These have control systems or evaporation sensors that switch the irrigation system on or off at regular intervals. Mist sprinklers create proper humidity. Selection of an irrigation system depends on the watering requirements of the plants.