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A greenhouse (also called a glass-house or hothouse) is a building where plants such as flowers and vegetables are grown. It usually has a glass or translucent plastic roof. Many greenhouses also have glass or plastic walls. Greenhouses warm up during the day via penetration of the sun's rays which heat the plants, soil and structure. This heat is given up gradually throughout the night.

Types of greenhouses

Greenhouses come in many shapes and sizes, with different functions. Some people have small greenhouses in their backyard, or as a lean-to attached to their home, called mini greenhouses, or tomato houses. They want to start off their seeds and seedlings in a protected environment as well as those growing plants that need warmer conditions. Others, wishing to extend their living space, have house extensions in the form of mini-conservatories. Commercial companies usually have larger greenhouses for horticultural purposes, but have more substantial structures for plant displays where the public is admitted. For the same reason, botanic gardens usually have a high proportion of greenhouses with substantial structures

Role of greenhouses

Many vegetables and flowers are grown in greenhouses in late winter and early spring, when it is still too cold to grow plants outside. Then these plants move into the soil outside as the weather warms up. Greenhouses are used to grow crops in cold countries such as Canada. The largest group of greenhouses in the world is in Leamington, Ontario (in Canada), where about 200 acres (0.8 km²) of tomatoes are grown in glass greenhouses.

Gardening in greenhouses

Gardening and growing plants in greenhouses is different from growing plants outside as no rain can get inside a greenhouse, so gardeners have to water plants. Also, greenhouses can get very hot from the sun's heat, so gardeners have to make sure that it does not get too hot for the plants. Greenhouses usually have vents that can be opened to let excess heat out. Some greenhouses have electric exhaust fans that automatically turn on if it gets too hot in the greenhouse. A greenhouse is the place for tender plants such as tomatoes, cucumbers, and aubergines.

Roman gardeners grew cucumbers in frames covered with oiled cloth or with sheets of mica. In the 1500s, Italian gardeners built structures for the tropical plants that explorers brought back to Italy. Jules Charles built the first modern greenhouse in Holland. In the 1800s, large greenhouses were built in England. The greenhouse concept also appeared in the Netherlands and then England in the 17th century

Woods, May (1988) Glass houses: history of greenhouses, orangeries and conservatories. Aurum Press, London, .

Mini Greenhouse nhà kính mini

Images for kids

Recreational Greenhouse at Palazzo Parisio, Malta.

Young tomato plants for transplanting in an industrial-sized greenhouse in the Netherlands

Greenhouses in the Westland region.

Victoria amazonica (giant Amazon waterlilies) in a large greenhouse at the Saint Petersburg Botanical Garden.

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A greenhouse (also called a glass-house or hothouse) is a building where plants such as flowers and vegetables are grown. It usually has a glass or translucent plastic roof. Many greenhouses also have glass or plastic walls. Greenhouses warm up during the day via penetration of the sun's rays which heat the plants, soil and structure.

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myON is here to help ensure your students can keep reading and learning even if schools close. To support you and your students, please see the learning and implementation resources available on our Renaissance at Home hub.

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myON is here to help ensure your students can keep reading and learning even if schools close. To support you and your students, please see the learning and implementation resources available on our Renaissance at Home hub.

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Growing North's Greenhouse in Naujaat, Nunavut. Image: Growing North

Growing North is exploring alternative and sustainable ways of feeding Canada's north by using some of the latest in vertical farming techniques.

What was a once far-fetched idea is now a sustainable option for providing food to a growing population. Vertical farming allows farmers to have a 365-day season without having to use pesticides or worry about traditional farming concerns like sunlight, rain, or drought.

Over the last ten years, a number of companies have popped up around the world using old warehouses and other unconventional urban spaces to grow fresh produce. Many of these farms operate in densely populated places like China, Japan, Belgium, and the United States. The largest floor-to-ceiling farm is currently in New Jersey at nearly 70,000 square feet. And the phenomenon is only going to get bigger. By some estimates, the vertical farming industry is projected to be worth USD $13 billion by 2024.

Bright Agrotech, a Wyoming startup, allows small urban and suburban farmers to grow crops through its vertical hydroponic farming systems. Hydroponic refers to soilless growing, in which the plants are grown using only nutrient-rich water. The water flows across the root structure and is taken up by the plants. Bright Agrotech's systems, which focus on greens and herbs is being used in Growing North's Naujaat greenhouse.

"Nunavut has the highest rate of food insecurity in Canada," Nieto told Motherboard in an interview. The organization estimates the price reductions on fresh produce grown in their greenhouses to be anywhere from 50 to 70 percent, depending on whether the produce is sold to local grocers or sold directly to consumers through places like the farmer's market.

"You can face food insecurity even living in a city like downtown Toronto if there is not a grocery store for miles around," explained Ben Canning, co-founder of Growing North.

Food inaccessibility persists in northern Canada, in large part, due to the cost of getting food to the region. Fresh food has to be flown in from the south. Each community faces its own challenges. Some are only accessible by road and not by air, which adds time and money. "Whether it's food or construction goods that need to shipped in, the farther north you go, the longer the supply chain gets and the more it costs. Even a lot of our food consumed in Toronto is shipped in. To get to the North, they spend an extra two weeks in cargo freights, craters, and planes," said Canning.

Growing North's current greenhouse is 75 percent hydroponic and 25 percent soil-based agriculture. The hydroponic system can grow any herb as well as greens like lettuce, kale, collard greens and swish chards. The agricultural side grows vegetables like radishes, potatoes, and carrots.

But the cost to construct these systems is extremely high-much higher than soil-based farming. For example, the 1300-square-foot dome shaped greenhouse in Naujaat cost Growing North about $100,000. For poor communities, especially in developing countries, vertical farming can be unaffordable. In addition to the initial costs, there are other ongoing expenses related to paying tech-savvy workers needed to run the farms. Currently, Growing North is working on lowering that cost through in-house research and development which would make project implementation in smaller communities with limited access to funds, possible.

Still, local greenhouses may be a viable answer to the problem of food accessibility in the north.
Correction: An earlier version of this story said the greenhouse produced 13,250 lbs of food last year, but that number actually represents its full capacity. The story has been updated.

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Greenhouses in the Arctic Will Reduce Food Insecurity in Canada's North

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Growing North's Greenhouse in Naujaat, Nunavut. Image: Growing North Growing North is exploring alternative and sustainable ways of feeding Canada's north by using some of the latest in vertical farming techniques. What was a once far-fetched idea is now a sustainable option for providing food to a growing population.

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Most cacti enjoy dry, hot environments, while orchids thrive in humid, tropical locales. Every plant has its ideal growing conditions, but sometimes Mother Nature does not cooperate. To create the best growing conditions for a specific plant or plant type, people devised buildings that could be climate-controlled. Greenhouses, conservatories or orangeries are usually framed in metal, wood or plastic. Then the frame is lined with panels of glass or polycarbonate, a clear form of heat-resistant plastic. The clear panels work to trap the sun's heat warming the building, yet gardeners must adjust ventilation accordingly to keep the building's temperature within the range needed for the plants.

Many of the first greenhouses were created to diversify or increase food supply. Now, greenhouses are still used to produce food, but others are used to grow plants for decoration, landscaping and educational purposes. In this article, we will explore 10 different greenhouses from around the world. We'll start in the United States.

The Big Apple borough of the Bronx is home to The New York Botanical Garden, which boasts two greenhouses among its many gardens. The Enid A. Haupt Conservatory is the largest Victorian-style glasshouse in the United States [source: Warren]. Opened in 1902 and restored in 1997, the conservatory is divided into different biomes filled with diverse plant species, including a substantial palm collection.

The Nolen Greenhouses for Living Collections opened at The New York Botanical Garden in 2005. The 43,000-square-foot (approximately 3,995-square-meter) structure has state-of-the-art climate-controlling capabilities such as open-roof ventilation, shade curtains and radiant heat flooring [source: The New York Botanical Garden]. The greenhouse's collection is divided into eight growing areas and includes aquatic plants, desert plants, orchids and ferns [source: The New York Botanical Garden].

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For an educational greenhouse with a kid-friendly atmosphere, head to Florida. Within the Epcot Theme Park of Walt Disney World, The Land pavilion houses a series of greenhouses. Guests can peek into The Land's four greenhouses -- the Tropics Greenhouse, the Temperate Greenhouse, the Production Greenhouse and the Creative Greenhouse -- when they take the 14-minute Living with the Land ride [source: Walt Disney World News]. Sites include Mickey Mouse-shaped pumpkins, a 59-foot (approximately 18-meter) tall peach palm and sweet potatoes growing without soil [source: Walt Disney World News].

For a more in-depth view of the greenhouses and the science behind many of the horticultural techniques used by the Disney scientists, buy tickets for the one-hour Behind the Seeds tour.

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Over the Atlantic Ocean in the United Kingdom, you can visit a horticultural attraction growing out of a former quarry. The Eden Project, which fully opened to the public in 2001, was created on the site of a china clay quarry in Cornwall, England [source: Eden Project]. The major features of the Eden Project are the greenhouses that resemble flexible clear beach balls growing out of the ground. The Rainforest Biome is kept at around 90 percent humidity and 75 degrees Fahrenheit (24 degrees Celsius) to create just the right tropical environment [source: Eden Project]. Higher than the Statue of Liberty at 50 meters tall (approximately 164 feet), the Rainforest Biome simulates a jungle feel with more than 1,000 different plant species, including banana plants, tropical ferns and even the rare Titan arum, or corpse flower, which packs a powerful smell [source: U.S. Department of the Interior and Eden Project].

The other enclosed greenhouse holds the Mediterranean Biome, which mimics the climate of South Africa and California. Guests will find a variety of plants that thrive in these warm, temperate conditions, including olive trees, orange trees and cork plants [source: Eden Project].

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You don't have to travel far to visit the next greenhouse on the list because it also hails from the United Kingdom.

Run by the famous Royal Horticultural Society, the RHS Garden Wisley is the society's premier garden. Located in southeast England in Surrey, the garden's signature icon is its new greenhouse -- the Glasshouse. Created for the Royal Horticultural Society's bicentenary, it was even officially opened by Her Majesty Queen Elizabeth [source: Royal Horticultural Society].

The Glasshouse resides on a peninsula in the middle of a lake surrounded by outdoor plantings. The actual 40-foot (12-meter) structure houses three different climate areas [source: Mahr]. The tropical zone includes a large waterfall feature and a pond filled with water lilies. The moist, temperate zone boasts tree ferns and palms, while in the dry, temperate zone, you can find cacti and succulents [source: Royal Horticultural Society].

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Well-known for tulips, wooden clogs and windmills, the Netherlands is also famous for its greenhouses. One region, in particular, is nicknamed the Glass City because of the number of greenhouses in a concentrated area. This part of the country is more formally referred to as the Westland, located on the western side of the Netherlands between The Hague and Rotterdam. It's one of the oldest and largest areas of greenhouse produce growers in the country. Key crops include sweet peppers, tomatoes, cucumbers and lettuce [source: The Royal Netherlands Embassy]. More than 50 percent of all fruits and vegetables produced in the country are grown in greenhouses [source: The Royal Netherlands Embassy].

Next, we will travel to a neighboring European nation.

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Just over the border in Belgium, a regal set of greenhouses grace the northern suburb of Brussels. Located on the grounds of the Royal Castle at Laeken, 6 acres (2.5 hectares) of greenhouses were created under the direction of King Leopold II by architect Alphonse Balat and took more than 30 years to build [source: The Belgian Monarchy and VisitFlanders]. Made of iron and glass, the 19 th-century greenhouses include a large collection of camellias, azaleas, palm trees and a variety of rare plant species [source: The Belgian Monarchy and VisitFlanders]. The Royal Greenhouses of Laeken are opened to the public for three weeks a year during the spring [source: The Belgian Monarchy].

The next greenhouse is located far north of Belgium in Scandinavia.

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In the capital of Finland, Helsinki, the city's center offers a green oasis during the frigid winter months. The City Winter Garden houses more than 200 different plants inside the three distinct rooms of the greenhouse [source: City of Helsinki, Public Works Department].The palm room is home to palms as well as the oldest plants in the greenhouse, more than hundred-year-old camellias. To catch the camellias' blooming, visit from October through February [source: VisitHelsinki]. The western room holds cycads and palmettos, while the last room is filled with cacti and other desert plants [source: City of Helsinki, Public Works Department].

For the next greenhouse, we travel far south to India.

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The capital of the Indian state of Karnataka, Bangalore, is sometimes referred to as the Garden City because of its many parks and green spaces [source: de Bruyn]. Bangalore's city center is home to the Lalbagh Botanical Garden. Starting out as the private 40-acre (approximately 16 hectare) garden of Hyder Ali, a ruler of Mysore in the 18th century, the garden now includes more than 240 acres (approximately 97 hectares) [source: The Directorate of Horticulture].The garden boasts about 1,800 species of plants, including ficus trees, bamboo, ferns, lotus, magnolia and cypress plants [sources: The Directorate of Horticulture and Caine].

One of Lalbagh's highlights is the Glass House. Built in 1889, the greenhouse was modeled after the glass-and-iron Crystal Palace in London, England [sources: BBC and The Directorate of Horticulture]. It's now best known for the biannual flower shows that take place within its walls.

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Located in South Africa, Kirstenbosch National Botanical Garden is only about 13 kilometers (approximately 8 miles) from the center of Cape Town and set on the eastern slope of Table Mountain [source: South Africa Tourism]. It's one of South Africa's oldest botanical gardens, having been founded in 1913, and also one of its largest at about 528 hectares (approximately 1,305 acres) [source: South African National Biodiversity Institute]. The botanical garden is unique because it displays only indigenous South African plants.

One of the highlights of the gardens is the Botanical Society Conservatory, completed in 1996. The 17,600-square-foot (approximately 1,600-square-meter) facility houses one main room and four smaller adjacent rooms [source: van Jaarsveld]. The conservatory is divided into areas by climate and location in South Africa. For example, if you're looking for a plant found in the northern region of South Africa, you would go to the northern part of the conservatory. Representing the arid conditions of South Africa, plantings include the baobab tree, succulents, bulbs, ferns, aloe plants and Fynbos vegetation unique to the Cape floral region of Africa [source: South African National Biodiversity Institute].

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Next, we head even further south to Antarctica.

The South Pole Food Growth Chamber is located inside the new Amundsen-Scott South Pole Station, dedicated in January 2008 [source: The National Science Foundation and Sorenson]. While technically not a greenhouse because it doesn't use sun to heat or grow the plants, it's still an enclosed growing chamber [source: The Associated Press].

Delivered to the South Pole in 2004, the chamber uses artificial light, carbon dioxide and hydroponics, which uses nutrient-rich water instead of soil to grow plants [source: Barber]. The chamber is about 18 feet by 28 feet (approximately 6 meters by 9 meters) and grows everything from lettuce to hot peppers [sources: Barber and McGinley]. The chamber yields about 60 to 100 pounds (27 to 45 kilograms) of produce a week to feed the staffers in the station [source: Sorenson]. Along with food production, the chamber also provides green plant life and sunlight for staffers to enjoy during the long winters in the barren landscape of Antarctica [source: Sorenson].

Scientists hope that the science related to this greenhouse will translate to outer space environments such as Mars [source: Sorenson].

Whether used as a display garden or a food-producing plot, greenhouses create environments that allow plants to thrive in a range of countries worldwide.

Related HowStuffWorks Articles

Related HowStuffWorks Articles

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Most cacti enjoy dry, hot environments, while orchids thrive in humid, tropical locales. Every plant has its ideal growing conditions, but sometimes Mother Nature does not cooperate. To create the best growing conditions for a specific plant or plant type, people devised buildings that could be climate-controlled.

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The greenhouse effect is a warming of Earth’s surface and the air above it. It is caused by gases in the air that trap energy from the Sun. These heat-trapping gases are…