Greenhouse
Overview
A greenhouse is a building in which plants are grown. These structures range in size from small sheds to very large buildings. A miniature greenhouse is known as a cold frame
Cold frame
In agriculture and gardening, a cold frame is a transparent-roofed enclosure, built low to the ground, used to protect plants from cold weather. The transparent top admits sunlight and prevents heat escape via convection that would otherwise occur, particularly at night...

.

A greenhouse is a structure with different types of covering materials, such as a glass or plastic roof and frequently glass or plastic walls; it heats up because incoming visible solar radiation (for which the glass is transparent) from the sun is absorbed by plants, soil, and other things inside the building.
Encyclopedia
A greenhouse is a building in which plants are grown. These structures range in size from small sheds to very large buildings. A miniature greenhouse is known as a cold frame
Cold frame
In agriculture and gardening, a cold frame is a transparent-roofed enclosure, built low to the ground, used to protect plants from cold weather. The transparent top admits sunlight and prevents heat escape via convection that would otherwise occur, particularly at night...

.

A greenhouse is a structure with different types of covering materials, such as a glass or plastic roof and frequently glass or plastic walls; it heats up because incoming visible solar radiation (for which the glass is transparent) from the sun is absorbed by plants, soil, and other things inside the building. Air warmed by the heat from hot interior surfaces is retained in the building by the roof and wall. In addition, the warmed structures and plants inside the greenhouse re-radiate some of their thermal energy in the infra-red, to which glass is partly opaque, so some of this energy is also trapped inside the glasshouse. However, this latter process is a minor player compared with the former (convective) process. Thus, the primary heating mechanism of a greenhouse is convection
Convection
Convection is the movement of molecules within fluids and rheids. It cannot take place in solids, since neither bulk current flows nor significant diffusion can take place in solids....

. This can be demonstrated by opening a small window near the roof of a greenhouse: the temperature drops considerably. This principle is the basis of the autovent
Autovent
An autovent is a device for maintaining a greenhouse or conservatory within a range of temperatures. The basic principle is that as greenhouse heats above ambient the air inside becomes lighter, the vent opens when a certain temperature is reached and lets the hot air out - drawing cooler air in...

 automatic cooling system. Thus, the glass used for a greenhouse works as a barrier to air flow, and its effect is to trap energy within the greenhouse. The air that is warmed near the ground is prevented from rising indefinitely and flowing away.

Although there is some heat loss due to thermal conduction through the glass and other building materials, there is a net increase in energy (and therefore temperature) inside the greenhouse.

Greenhouses can be divided into glass greenhouses and plastic greenhouses.
Plastics mostly used are PE
Polyethylene
Polyethylene or polythene is the most widely used plastic, with an annual production of approximately 80 million metric tons...

film and multiwall sheet in PC or PMMA
Acrylic glass
Poly is a transparent thermoplastic, often used as a light or shatter-resistant alternative to glass. It is sometimes called acrylic glass. Chemically, it is the synthetic polymer of methyl methacrylate...

.
Commercial glass greenhouses are often high tech production facilities for vegetables or flowers. The glass greenhouses are filled with equipment like screening installations, heating, cooling, lighting and may be automatically controlled by a computer.

Uses

Greenhouses protect crops from too much heat or cold and help to keep out pests. Light and temperature control allows greenhouses to turn inarable land into arable land
Arable land
In geography and agriculture, arable land is land that can be used for growing crops. It includes all land under temporary crops , temporary meadows for mowing or pasture, land under market and kitchen gardens and land temporarily fallow...

, thereby improving food production in marginal environments.

Because greenhouses allow certain crops to be grown throughout the year, greenhouses are increasingly important in the food supply of high latitude countries. One of the largest greenhouse complexes in the world is in Almeria, Spain, where greenhouses cover almost 50000 acres (202.3 km²). Sometimes called the sea of plastics.

Greenhouses are often used for growing flowers
Floriculture
Floriculture, or flower farming, is a discipline of horticulture concerned with the cultivation of flowering and ornamental plants for gardens and for floristry, comprising the floral industry...

, vegetable
Vegetable
The noun vegetable usually means an edible plant or part of a plant other than a sweet fruit or seed. This typically means the leaf, stem, or root of a plant....

s, fruit
Fruit
In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...

s, and tobacco
Tobacco
Tobacco is an agricultural product processed from the leaves of plants in the genus Nicotiana. It can be consumed, used as a pesticide and, in the form of nicotine tartrate, used in some medicines...

 plants. Bumblebee
Bumblebee
A bumble bee is any member of the bee genus Bombus, in the family Apidae. There are over 250 known species, existing primarily in the Northern Hemisphere although they are common in New Zealand and in the Australian state of Tasmania.Bumble bees are social insects that are characterised by black...

s are the pollinator
Pollinator
A pollinator is the biotic agent that moves pollen from the male anthers of a flower to the female stigma of a flower to accomplish fertilization or syngamy of the female gamete in the ovule of the flower by the male gamete from the pollen grain...

s of choice for most greenhouse pollination
Pollination
Pollination is the process by which pollen is transferred in plants, thereby enabling fertilisation and sexual reproduction. Pollen grains transport the male gametes to where the female gamete are contained within the carpel; in gymnosperms the pollen is directly applied to the ovule itself...

, although other types of bee
Bee
Bees are flying insects closely related to wasps and ants, and are known for their role in pollination and for producing honey and beeswax. Bees are a monophyletic lineage within the superfamily Apoidea, presently classified by the unranked taxon name Anthophila...

s have been used, as well as artificial pollination. Hydroponics
Hydroponics
Hydroponics is a method of growing plants using mineral nutrient solutions, in water, without soil. Terrestrial plants may be grown with their roots in the mineral nutrient solution only or in an inert medium, such as perlite, gravel, mineral wool, or coconut husk.Researchers discovered in the 18th...

 can be used in greenhouses as well to make the most use of the interior space.

Besides tobacco, many vegetables and flowers are grown in greenhouses in late winter and early spring, and then transplanted outside as the weather warms. Started plants are usually available for gardeners in farmers' market
Farmers' market
A farmers' market consists of individual vendors—mostly farmers—who set up booths, tables or stands, outdoors or indoors, to sell produce, meat products, fruits and sometimes prepared foods and beverages...

s at transplanting time. Special greenhouse varieties of certain crops such as tomatoes are generally used for commercial production.

The closed environment of a greenhouse has its own unique requirements, compared with outdoor production. Pest
Pest (animal)
A pest is an animal which is detrimental to humans or human concerns. It is a loosely defined term, often overlapping with the related terms vermin, weeds, parasites and pathogens...

s and disease
Disease
A disease is an abnormal condition affecting the body of an organism. It is often construed to be a medical condition associated with specific symptoms and signs. It may be caused by external factors, such as infectious disease, or it may be caused by internal dysfunctions, such as autoimmune...

s, and extremes of heat and humidity, have to be controlled, and irrigation
Irrigation
Irrigation may be defined as the science of artificial application of water to the land or soil. It is used to assist in the growing of agricultural crops, maintenance of landscapes, and revegetation of disturbed soils in dry areas and during periods of inadequate rainfall...

 is necessary to provide water. Significant inputs of heat and light may be required, particularly with winter production of warm-weather vegetables.

Because the temperature and humidity of greenhouses must be constantly monitored to ensure optimal conditions, a wireless sensor network
Wireless sensor network
A wireless sensor network consists of spatially distributed autonomous sensors to monitor physical or environmental conditions, such as temperature, sound, vibration, pressure, motion or pollutants and to cooperatively pass their data through the network to a main location. The more modern...

 can be used to gather data remotely. The data is transmitted to a control location and used to control heating, cooling, and irrigation systems.

History

The idea of growing plants in environmentally controlled areas has existed since Roman
Ancient Rome
Ancient Rome was a thriving civilization that grew on the Italian Peninsula as early as the 8th century BC. Located along the Mediterranean Sea and centered on the city of Rome, it expanded to one of the largest empires in the ancient world....

 times. The Roman emperor Tiberius
Tiberius
Tiberius , was Roman Emperor from 14 AD to 37 AD. Tiberius was by birth a Claudian, son of Tiberius Claudius Nero and Livia Drusilla. His mother divorced Nero and married Augustus in 39 BC, making him a step-son of Octavian...

 ate a cucumber-like
Armenian cucumber
The Armenian cucumber, Cucumis melo var. flexuosus, is a type of long, slender fruit which tastes like a cucumber and looks somewhat like a cucumber inside. It is actually a variety of muskmelon , a species closely related to the cucumber...

 vegetable daily. The Roman gardeners used artificial methods (similar to the greenhouse system) of growing to have it available for his table every day of the year. Cucumbers were planted in wheeled carts which were put in the sun daily, then taken inside to keep them warm at night. The cucumbers were stored under frames or in cucumber houses glazed with either oiled cloth known as "specularia" or with sheets of selenite (a.k.a. lapis specularis), according to the description by Pliny the Elder
Pliny the Elder
Gaius Plinius Secundus , better known as Pliny the Elder, was a Roman author, naturalist, and natural philosopher, as well as naval and army commander of the early Roman Empire, and personal friend of the emperor Vespasian...

.

The first modern greenhouses were built in Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...

 in the 13th century to house the exotic plants that explorers brought back from the tropics. They were originally called giardini botanici (botanical gardens). The concept of greenhouses soon spread to the Netherlands
Netherlands
The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...

 and then England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

, along with the plants. Some of these early attempts required enormous amounts of work to close up at night or to winterize. There were serious problems with providing adequate and balanced heat in these early greenhouses. Today the Netherlands has many of the largest greenhouses in the world, some of them so vast that they are able to produce millions of vegetables every year.

The French botanist Charles Lucien Bonaparte
Charles Lucien Bonaparte
Charles Lucien Jules Laurent Bonaparte, 2nd Prince of Canino and Musignano was a French naturalist and ornithologist.-Biography:...

 is often credited with building the first practical modern greenhouse in Leiden, Holland to grow medicinal tropical plants.

Originally on the estates of the rich, with the growth of the science of botany
Botany
Botany, plant science, or plant biology is a branch of biology that involves the scientific study of plant life. Traditionally, botany also included the study of fungi, algae and viruses...

, greenhouses spread to the universities. The French called their first greenhouses orangeries, since they were used to protect orange trees from freezing. As pineapples became popular pineries, or pineapple pits
Pineapple Pit
A pineapple pit is a method of growing pineapples in colder climates.This method of cultivation was invented by gardeners in the UK, during the Victorian era.-Method of cultivation:...

, were built. Experimentation with the design of greenhouses continued during the Seventeenth Century in Europe as technology produced better glass and construction techniques improved. The greenhouse at the Palace of Versailles
Palace of Versailles
The Palace of Versailles , or simply Versailles, is a royal château in Versailles in the Île-de-France region of France. In French it is the Château de Versailles....

 was an example of their size and elaborateness; it was more than 500 feet (152.4 m) long, 42 feet (12.8 m) wide, and 45 feet (13.7 m) high.

In the nineteenth Century the largest greenhouses were built. The conservatory at Kew Gardens in England is a prime example of the Victorian greenhouse. Although intended for both horticultural
Horticulture
Horticulture is the industry and science of plant cultivation including the process of preparing soil for the planting of seeds, tubers, or cuttings. Horticulturists work and conduct research in the disciplines of plant propagation and cultivation, crop production, plant breeding and genetic...

 and non-horticultural exhibition these included London's Crystal Palace
The Crystal Palace
The Crystal Palace was a cast-iron and glass building originally erected in Hyde Park, London, England, to house the Great Exhibition of 1851. More than 14,000 exhibitors from around the world gathered in the Palace's of exhibition space to display examples of the latest technology developed in...

, the New York Crystal Palace
Exhibition of the Industry of All Nations
Exhibition of the Industry of All Nations was a World's Fair held in 1853 in New York City, in the wake of the highly successful 1851 Great Exhibition in London. It aimed to showcase the new industrial achievements of the world and also to demonstrate the nationalistic pride of a relatively young...

 and Munich
Munich
Munich The city's motto is "" . Before 2006, it was "Weltstadt mit Herz" . Its native name, , is derived from the Old High German Munichen, meaning "by the monks' place". The city's name derives from the monks of the Benedictine order who founded the city; hence the monk depicted on the city's coat...

’s Glaspalast
Glaspalast
Glaspalast may refer to:*Glaspalast , Glaspalast in Munich modeled after The Crystal Palace*Glaspalast , an indoor arena in Sindelfingen...

. Joseph Paxton, who had experimented with glass and iron in the creation of large greenhouses as the head gardener at Chatsworth
Chatsworth House
Chatsworth House is a stately home in North Derbyshire, England, northeast of Bakewell and west of Chesterfield . It is the seat of the Duke of Devonshire, and has been home to his family, the Cavendish family, since Bess of Hardwick settled at Chatsworth in 1549.Standing on the east bank of the...

, in Derbyshire
Derbyshire
Derbyshire is a county in the East Midlands of England. A substantial portion of the Peak District National Park lies within Derbyshire. The northern part of Derbyshire overlaps with the Pennines, a famous chain of hills and mountains. The county contains within its boundary of approx...

, working for the Duke of Devonshire
Duke of Devonshire
Duke of Devonshire is a title in the peerage of England held by members of the Cavendish family. This branch of the Cavendish family has been one of the richest and most influential aristocratic families in England since the 16th century, and have been rivalled in political influence perhaps only...

, designed and built the first, London's Crystal Palace
The Crystal Palace
The Crystal Palace was a cast-iron and glass building originally erected in Hyde Park, London, England, to house the Great Exhibition of 1851. More than 14,000 exhibitors from around the world gathered in the Palace's of exhibition space to display examples of the latest technology developed in...

. A major architectural achievement in monumental greenhouse building were the Royal Greenhouses of Laeken
Royal Greenhouses of Laeken
The Royal Greenhouses of Laeken , are a vast complex of monumental heated greenhouses in the park of the Royal Castle of Laeken in Brussels and one of the major tourist attractions of the city. The complex was commissioned by King Leopold II of Belgium and designed by Alphonse Balat...

 (1874–1895) for King Leopold II of Belgium.

In Japan, the first greenhouse was built in 1880 by Samuel Cocking
Samuel Cocking
Samuel Cocking was a British trader in Yokohama arriving in 1869, shortly after the “Opening of Japan”. He is most famous for the large greenhouse and gardens that he developed in Enoshima...

, a British merchant who exported herbs.

In the Twentieth Century the geodesic dome
Geodesic dome
A geodesic dome is a spherical or partial-spherical shell structure or lattice shell based on a network of great circles on the surface of a sphere. The geodesics intersect to form triangular elements that have local triangular rigidity and also distribute the stress across the structure. When...

 was added to the many types of greenhouses. A notable example is the Eden Project
Eden Project
The Eden Project is a visitor attraction in Cornwall in the United Kingdom, including the world's largest greenhouse. Inside the artificial biomes are plants that are collected from all around the world....

, in Cornwall
Cornwall
Cornwall is a unitary authority and ceremonial county of England, within the United Kingdom. It is bordered to the north and west by the Celtic Sea, to the south by the English Channel, and to the east by the county of Devon, over the River Tamar. Cornwall has a population of , and covers an area of...

.

Greenhouse structures adapted in the 1960s when wider sheets of polyethylene film became widely available. Hoop houses were made by several companies and were also frequently made by the growers themselves. Constructed of aluminium extrusions, special galvanized steel tubing, or even just lengths of steel or PVC water pipe, construction costs were greatly reduced. This meant many more greenhouses on smaller farms and garden centers. Polyethylene film durability increased greatly when more effective inhibitors were developed and added in the 1970s. These UV inhibitors extended the usable life of the film from one or two years up to 3 and eventually 4 or more years.

Gutter-connected greenhouses became more prevalent in the 1980s and 1990s. These greenhouses have two or more bays connected by a common wall, or row of support posts. Heating inputs were reduced as the ratio of floor area to roof area was increased substantially. Gutter connected greenhouses are now commonly used both in production and in situations where plants are grown and sold to the public as well. Gutter connected greenhouses are commonly covered with a double layer of polyethylene film with air blown between to provide increased heating efficiencies, or structured polycarbonate materials.

Netherlands

The Netherlands has some of the largest greenhouses in the world. Such is the scale of food production in the country that in 2000, greenhouses occupied 10,526 hectares, or 0.25% of the total land area of the Netherlands.

Greenhouses began to be built in the Westland
Westland (region), Netherlands
Westland is a region of the Netherlands and lies in the western part of the Province of South Holland. It consists of the municipalities of Westland and Midden-Delfland, and also of the town of Hook of Holland .Westland is well-known for its horticulture in glasshouses....

 area of the Netherlands in the mid-nineteenth century. The addition of sand to bogs and clay soil created fertile soil for agriculture, and around 1850, grapes were grown in the first greenhouses, simple glass constructions with one of the sides consisting of solid wall. By the early 20th century, greenhouses began to be constructed of nothing but glass, and they began to be heated. This also allowed for the production of fruits and vegetables that did not ordinarily grow in the area. Today, the Westland and the area around Aalsmeer
Aalsmeer
Aalsmeer is a municipality and a town in the Netherlands, in the province of North Holland. Its name is derived from the Dutch for eel and lake . Aalsmeer is bordered by the Westeinderplassen lake, the largest open water of the Randstad, and the Ringvaart Canal...

 have the highest concentration of greenhouse agriculture in the world. The Westland produces mostly vegetables, besides plants and flowers; Aalsmeer is noted mainly for the production of flowers and potted plants. Since the twentieth century, the area around Venlo
Venlo
Venlo is a municipality and a city in the southeastern Netherlands, next to the German border. It is situated in the province of Limburg.In 2001, the municipalities of Belfeld and Tegelen were merged into the municipality of Venlo. Tegelen was originally part of the Duchy of Jülich centuries ago,...

 and parts of Drenthe
Drenthe
Drenthe is a province of the Netherlands, located in the north-east of the country. The capital city is Assen. It is bordered by Overijssel to the south, Friesland to the west, Groningen to the north, and Germany to the east.-History:Drenthe, unlike many other parts of the Netherlands, has been a...

 have also become important regions for greenhouse agriculture.
Since 2000, technical innovations include the "closed greenhouse", a completely closed system allowing the grower complete control over the growing process while using less energy. Floating greenhouses are used in watery areas of the country.

The Netherlands has around 9,000 greenhouse enterprises that operate over 10,000 hectares of greenhouses and employ some 150,000 workers, efficiently producing €4.5 billion worth of vegetables, fruit, plants, and flowers, some 80% of which is exported.

Greenhouse ventilation

Ventilation
Ventilation (architecture)
Ventilating is the process of "changing" or replacing air in any space to provide high indoor air quality...

 is one of the most important components in a successful greenhouse. If there is no proper ventilation, greenhouses and their plants become prone to myriad problems.

Ventilation serves four major purposes within the greenhouse:
  • Regulating the temperature
  • Ensurance of plenty of fresh air to photosynthesize
  • Good ventilation prevents pest infestations
  • Encouraging important pollination within the greenhouse


In greenhouses recirculation fans can be used in parallel or series ventilation.

Siting

Siting a greenhouse is huge consideration. In the Northern Hemisphere the side with the largest surface area should face south. The rule is reversed in the Southern Hemisphere. The greenhouse should get as much unobstructed light as possible. Considerations are given to deciduous trees which will lose their leaves and permit light penetration and also coniferous trees which will generally always block light. The greenhouse site must also be leveled.

See also

  • Bioshelter
    Bioshelter
    A bioshelter is a solar greenhouse managed as an indoor ecosystem. The word bioshelter was coined by the New Alchemy Institute and solar designers Sean Wellesley-Miller and Day Chahroudi...

  • Biosphere 2
    Biosphere 2
    Biosphere 2 is a structure originally built to be an artificial, materially-closed ecological system in Oracle, Arizona by Space Biosphere Ventures, a joint venture whose principal officers were John P. Allen, inventor and Executive Director, and Margret Augustine, CEO...

  • Conservatory (greenhouse)
    Conservatory (greenhouse)
    A conservatory is a room having glass roof and walls, typically attached to a house on only one side, used as a greenhouse or a sunroom...

  • Garden conservatory
  • Greenhouse effect
    Greenhouse effect
    The greenhouse effect is a process by which thermal radiation from a planetary surface is absorbed by atmospheric greenhouse gases, and is re-radiated in all directions. Since part of this re-radiation is back towards the surface, energy is transferred to the surface and the lower atmosphere...

  • Phytotron
    Phytotron
    A phytotron is an enclosed research greenhouse used for studying interactions between plants and the atmosphere.-External links:*...

  • Royal Greenhouses of Laeken
    Royal Greenhouses of Laeken
    The Royal Greenhouses of Laeken , are a vast complex of monumental heated greenhouses in the park of the Royal Castle of Laeken in Brussels and one of the major tourist attractions of the city. The complex was commissioned by King Leopold II of Belgium and designed by Alphonse Balat...

     in Belgium
  • Seasonal thermal store
    Seasonal thermal store
    A seasonal thermal store is a store designed to retain heat deposited during the hot summer months for use during colder winter weather...

  • Tessellated roof
    Tessellated roof
    In architecture a tessellated roof is a frame and a self-supporting structural system.A simple ridged roof may inside be a tessellated system, it is built in many types of buildings...

  • The Eden Project
  • Vertical farming
    Vertical farming
    Vertical farming is a concept that argues that it is economically and environmentally viable to cultivate plant or animal life within skyscrapers, or on vertically inclined surfaces...

  • High tunnel
    High tunnel
    High tunnels are unheated, plastic-covered structures that provide an intermediate level of environmental protection and control compared to open field conditions or heated greenhouses....

  • Cold frame
    Cold frame
    In agriculture and gardening, a cold frame is a transparent-roofed enclosure, built low to the ground, used to protect plants from cold weather. The transparent top admits sunlight and prevents heat escape via convection that would otherwise occur, particularly at night...

  • Row cover
    Row cover
    In horticulture, row cover is any material used as a protective covering to shield plants, usually vegetables, primarily from the undesirable effects of cold and wind, and also from insect damage....

     (Cloche)
  • greenhouse gas
    Greenhouse gas
    A greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone...


External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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