The UN Food and Agriculture Organization estimates that 800 million people grow food in and around cities. That’s roughly 20% of the world’s urban population farming in one form or another.

Urban agriculture is common in many developing countries where people spend a far higher share of their income on buying food, but the practice is also becoming more popular globally.

Farms are springing up between high-rises, in shipping containers and on rooftops in cities around the world – and at a surprising scale. These urban farms are not only providing fresh produce for local people but also employment.

 A vertical farm inside a shipping container.
Image: Freightfarms.com

In the US, the urban agriculture movement has been flourishing for some years. Brooklyn Grange, situated on two rooftops in New York City, grows over 22,500kg of organic produce. And on top of a factory in Chicago sits the world’s largest rooftop greenhouse – measuring almost 7,000 square meters.

 The world’s largest rooftop greenhouse is on a Chicago factory
Image: gothamgreens.com

In an old warehouse in Newark, New Jersey, an even more ambitious project is taking shape. AeroFarms is building what it claims is the world’s largest vertical farm, producing around 900,000kg of leafy greens a year.

The greens are produced using aeroponics, an agricultural technique which involves growing crops in beds stacked vertically, without the use of soil, sunlight or pesticides, and with very little water

 Plants grown using the aeroponics technique do not require soil or sunlight
Image: Aerofarms.com

Vertical farming produces higher yields in far less space than traditional agriculture and its proponents say it reduces pressure on the environment and ultimately could improve food security.

The World Economic Forum lists “vertical vegetables” among its Top 10 Urban Innovations, arguing that moving the farm to the consumer’s doorstep cuts “a lot of waste out of the system”.

The technology has been embraced in Japan and Singapore, where land is scarce and expensive.

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Feeding a growing world

More and more people are moving to cities. Today just over half (54%) of the world’s population lives in urban areas. By 2050 this figure will be 66%, with most of the growth concentrated in Africa and Asia.

Growing food on vertical farms could help to ensure they will have enough to eat, supporters of the technology argue.

Other urban farmers, meanwhile, have been working on much lower-tech solutions to food security. In the Kibera slum in Nairobi, Kenya, residents grow vegetables vertically in sacks filled with manure, soil and small stones to allow water to drain, planting up the sides as well as at the top of sacks to maximize space.

Known as the sack gardens of Kibera, the initiative aimed to provide jobs for the unemployed as well as feeding people. Now there are thousands of these mini urban farms across the slum, which is home to around 700,000 people.

 The sack farming initiative in Kibera, Nairobi.
Image: Patrick Mayoyo/theguardian.com