- Also called:
- glasshouse
greenhouse
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What is a greenhouse?
A greenhouse is a framed structure enclosed with glass or plastic that allows sufficient sunlight to enter for photosynthesis. Greenhouses protect plants from excessive cold or heat, making it possible to grow fruits, vegetables, flowers, and other plants that require specific temperature conditions, regardless of the outside climate.
Modern greenhouses range in size from small units for home use to large commercial operations. Heating systems, such as those using hot water or warm air, are controlled by thermostat. Cooling systems, like ventilation or refrigeration, may also be necessary.
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How does a greenhouse help plants grow?
Greenhouses protect plants from extreme temperatures, whether from excessive cold or heat. The transparent or translucent roofs and sides allow sufficient sunlight to enter for photosynthesis. Greenhouses control interior temperature and humidity, enabling crop growing independent of the external climate. They range from small home structures to large commercial units and can be made of glass panes or plastic film. Heating systems, like hot water or electric cables, and cooling systems, like ventilation, help maintain specific temperatures for different plants.
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What materials are commonly used to build a greenhouse?
Modern greenhouses are framed structures that are typically enclosed with glass or plastic and used to protect plants from excessive cold or heat.
Commonly used materials:
* Glazing Glass, polyethylene, polyvinyl, and fiberglass
* Framing Aluminum, galvanized steel, redwood, cedar, and cypressGreenhouses also require systems for heating and ventilation, such as electric fans, roof openings, and end-wall openings.
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How does a greenhouse keep heat inside?
A greenhouse is designed to protect plants from excessive cold or heat. Greenhouses are typically enclosed structures with transparent or translucent roofs and sides, which allow sufficient solar radiation to enter for photosynthesis. The interior temperature and humidity can be controlled, enabling crop growing independent of the outside climate.
The greenhouse effect occurs when solar radiation converts into heat. Shortwave solar radiation selectively transmits through the atmosphere and is absorbed by the planet's surface. It is then re-radiated as infrared, which atmospheric gases absorb and partly re-radiate back to the surface. Ventilation systems consisting of roof and end-wall openings are needed to avoid overheating.
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What types of plants are often grown in greenhouses?
Greenhouses are structures that allow the cultivation of plants independent of the external climate by controlling interior temperature and humidity. They are used for growing fruits, vegetables, flowers, and other plants that need specific temperature conditions.
Plants grown in greenhouses are categorized based on their nighttime temperature requirements. Cool greenhouses (7–10 °C) are suitable for azaleas, carnations, daffodils, and tulips. Warm greenhouses (10–13 °C) are used for begonias, orchids, roses, and ferns. Tropical greenhouses (16–21 °C) can support caladiums, gardenias, palms, and passionflowers. Commercial greenhouses also grow tomatoes and other warm-weather vegetables.
Maintaining optimal greenhouse conditions involves regulating temperature, ventilation, sunlight, soil moisture, and pollination. Vigilance is needed to prevent diseases, which pose a serious hazard in greenhouse farming.
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How do modern technologies, like automatic watering or climate control, improve greenhouse farming?
Modern technologies significantly improve greenhouse farming by creating optimal, controlled environments for plant growth. Automatic watering systems ensure consistent soil moisture, preventing over or under-watering, while climate control systems regulate temperature and humidity using thermostats, ventilation, and cooling technologies. These systems maintain ideal conditions for specific crops, maximizing photosynthetic efficiency through supplementary carbon dioxide. Additionally, light and shade regulation optimize light exposure, and automated systems manage soil fertility. Although expensive, air-conditioning units can be used for scientific work requiring precise environmental control.
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greenhouse, building designed for the protection of tender or out-of-season plants against excessive cold or heat. In the 17th century, greenhouses were ordinary brick or timber shelters with a normal proportion of window space and some means of heating. As glass became cheaper and as more sophisticated forms of heating became available, the greenhouse evolved into a roofed and walled structure built of glass with a minimal wooden or metal skeleton. By the middle of the 19th century, the greenhouse had developed from a mere refuge from a hostile climate into a controlled environment, adapted to the needs of particular plants. A huge increase in the availability of exotic plants in the 19th century led to a vast increase in glasshouse culture in England and elsewhere. Large greenhouses are important in agriculture and horticulture and for botanical science, while smaller structures are commonly used by hobbyists, collectors, and home gardeners.
The modern greenhouse is usually a glass- or plastic-enclosed framed structure that is used for the production of fruits, vegetables, flowers, and any other plants that require special conditions of temperature. The basic structural forms are the span-type greenhouse, which has a double-sloped, or A-shaped, roof, and the lean-to greenhouse, which has only one roof slope and leans against the side of a building. Two or more span-type greenhouses are sometimes joined side by side so that they have fewer external walls, and heating costs are consequently less. A greenhouse has a large expanse of glazing on its sides and roof so that the plants are exposed to natural light for much of the day. Glass has been the traditional glazing material, but plastic films, such as polyethylene or polyvinyl, and fibreglass are also common. The framing of the structure is made of aluminum, galvanized steel, or such woods as redwood, cedar, or cypress. A greenhouse is heated partly by the rays of the Sun and partly by artificial means, such as circulating steam, hot water, or hot air. Because a greenhouse can become too hot as well as too cold, some type of ventilating system is also needed; this usually consists of roof openings, which can be operated mechanically or automatically, and end-wall openings, through which electric fans draw air and circulate it throughout the interior.
The plants grown in greenhouses fall into several broad categories based on their temperature requirements during nighttime hours. In a cool greenhouse, the nighttime temperature falls to about 7–10 °C (45–50 °F). Among the plants suited to cool greenhouses are azaleas, cinerarias, cyclamens, carnations, fuchsias, geraniums, sweet peas, snapdragons, and a variety of bulbous plants including daffodils, irises, tulips, hyacinths, and narcissi. A warm greenhouse has nighttime temperatures of 10–13 °C (50–55 °F). Begonias, gloxinias, African violets, chrysanthemums, orchids, roses, coleuses, and many kinds of ferns and cacti and other succulents are suited to such temperatures. In a tropical greenhouse, or hothouse, which has nighttime temperatures of 16–21 °C (60–70 °F), caladiums, philodendrons, gardenias, poinsettias, bougainvilleas, passionflowers, and many kinds of palms and orchids can be grown. In countries with cool climates, commercial greenhouses are used to grow tomatoes and other warm-weather vegetables. See also conservatory.
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