A counter-revolution called "urban farming" is fast growing toward the late summer harvest. What sounds like an oxymoron is destined to bring together things that are traditionally kept separate – urban and rural life. In New York, Berlin, Tokyo and Los Angeles, urban hipsters armed with hoes and spades are working between the high-rises and highways to till vegetables. This trendy phenomenon has already morphed into an international movement, alongside fraternal campaigns such as the processions worldwide in honor of US urban planning theorist and activist Jane Jacobs last May. Self-providers of the world, unite!

This city gardening eco-lifestyle can be associated with ciphers such as "Flower Power", a slogan for a zeitgeist that has many sources of inspiration. Since the initial situation (living conditions, relationship to the city, urban traditions) of the respective eco-asphalt idyllists differ greatly, the movement is hardly homogeneous worldwide. The core idea, however, is to grow a more open notion of the city: the city is not considered as something we simply encounter, but as a creative task to be tackled democratically. Behind this lurks the wish to work together as a community to produce healthy food. In times of Monsanto, GM-food and gentrification, threatened or lost spaces in the city are grabbed by the root. Local control is held up as a counter-model to ongoing globalization.

An ecological rethink plays a crucial role here. As early as 2030, 70 percent of the global population will be living in cities. And that will only be possible if conurbations adjust and change – creating a better microclimate with self-provision, more efficient use of waste and reduced transport volumes. The sustainability-oriented urban planning of an increasingly urbanized world has already been given its own label: "Ecological urbanism" is how landscape architect Charles Waldheim of the Graduate School of Design at Harvard University terms the creative formula for a green urbanity, in which opposites like the city and the country are no longer to have any relevance.

Gardening in the city is nothing new. Yet in the US, ideas such as the "Garden City" or "City Beautiful Movement" are marginal phenomena. As early as the end of the 19th century they sought to bring displaced greenery back into the growing, modern cities. Likewise, Frank Lloyd Wright's idea of allotting every American a plot of land was no more than an audacious vision. A German garden-plot culture, like that which promised workers a form of balance in densely built-up industrial towns in the late 19th century, is more or less unknown in the United States. That said, in America too it is traditional to use urban fallow land in times of crisis and supply bottlenecks – as was usual all over Germany after the Second World War, for instance, when for a time cows grazed and potatoes were planted at Tiergarten in Berlin. The kitchen gardens planted in the US as early as the First World War were revived in 1943 by First Lady Eleanor Roosevelt, with her famous vegetable patch. Even in the late 1940s these so-called "victory gardens" were supplying 40 percent of North America's entire vegetable market. Many of them still exist today.

Nevertheless, in the last century the sacred front lawn of people's properties has well and truly displaced the colorful kitchen garden. The tended green spaces symbolize the understanding of equality enshrined in the American Constitution. Now, the booming "urban farming" and "local food" movement targets this monoculture and sterile "American Beauty" world. For this reason, Fritz Haeg has called his book for self-providers "Attack on the Front Lawn". Even First Lady Michelle Obama is joining in, generating plenty of media attention along the way, and is nurturing a vegetable garden. The aim is to encourage Americans to adopt a more healthy, less alienated eating behavior. Yet what in the case of the government vegetable patch already has an unofficial character, otherwise grows free and wild from the grass roots.

Essentially, urban farming is always an alternative movement, even if chic gardens are now springing up on the rooftop terraces of Fifth Avenue in New York, in order to wrest a little friendly green from the concrete jungle that is Manhattan. The significance of "urban farming" is assuming a more central role in the decaying ghost towns of America, where it is becoming a tangible survival tool, so to speak. Many American towns are dominated by social and urban emptiness, which is also the result of an original American incomprehension of urban culture. The financial crisis has further exacerbated the situation of many poor inner-city districts. In ruined areas such as these, urban gardening is now increasingly becoming a way of creating more humane living conditions. By using disused, fallow land for food production, people can at the same time stabilize social networks and create functioning neighborhoods.

For the capital of the American urban farming movement is also the capital of the shrinking cities: Detroit – America's battered Motor City, where all the evils destroying the city befell it at the same time, namely cars and highways, the reduction of public transport, bankrupt urban planning departments, the separation of living conditions owing to decades of urban sprawl, "white flight" and ghettoization. Today, one third of the city lies fallow or consists of ruins. Over a million inhabitants have left the city in the last 50 years and will not be going back.

In this tattered urban space, surrounded as it is by suburbs like a donut, where even the big chains do not have stores providing necessary supplies, a serious grassroots movement has been thriving for some years now, bringing life to decay and emptiness. The model is so successful that a Detroit millionaire has unveiled a plan to build the world's largest "urban farm" in the city. For that to happen, however, even in Detroit residents would have to be relocated.

As the fate of the hippie commune "Freetown Christiania" in Copenhagen shows, or "Rolleimer" in Berlin, which has now virtually sunk into oblivion, alternative projects to revitalize urban areas are generally short-lived. At some point they always buckle under political pressure or rising land prices. The free cultivation of cucumbers and tomatoes only works when the real estate market is slack. As soon as urban areas become more attractive again, fallow land disappears. Indeed, in Detroit, which with its extreme conditions has become something of a laboratory for urban planners, urban farming has for a long time meant more than just crisis management or establishing an Eldorado for drop-outs. It is the inspiring little plant of an entirely new city identity. Some people already claim to see another city emerging from the ruins here, clusters of small village communities growing from green surroundings, a future taking shape that is half village and half city.

Indeed, there is nowhere that better illustrates what urban farming can be. As early as the 1950s, German immigrant Ludwig Hilberseimer, a landscape architect, had guessed what humans would need following the industrial destruction. When he designed Lafayette Park in Detroit together with Mies van der Rohe as part of an urban renewal project, with townhouses and high-rises, Hilberseimer repeatedly called for gardens where people could grow their own vegetables. In vain. Only now, it seems, half a century later, has Detroit taken the hint. Or, as Harvard lecturer Dorothée Imbert puts it: Self-provision gardens lend a modern society moral and economic stability. In short, they are indispensable.