When we think of fresh vegetables in the city, we often think of the farmers market. Now a staple of many an urban neighborhood, farmers markets provide a space for connecting the urban with the rural, bringing together the growers of our food with those who eat it in a celebration of one of the planet’s most elemental transactions. But while the shoppers at farmers markets tend to be intensely local, many walking from nearby residential areas, most of the vendors truck their wares in from outlying rural areas—an average of 56 miles for a piece of produce sold as “local,” according to the Leopold Center for Sustainable Agriculture. That’s a far cry from the 1,500 miles that the average American supermarket vegetable travels before it’s eaten. But with nearly 80 percent of Americans now living in urban areas and food transportation energy accounting for as much as two-thirds of the energy required to grow it, there’s a powerful argument to be made for keeping the foods we grow, buy, and eat even closer to home—in the backyards, vacant lots, and rooftops of even our most densely built urban areas.

Why grow food in the city?

A lower carbon footprintis far from the only benefit that an increasing number of urban farmers, gardeners, and consumers have realized through growing and buying food right where they live. Urban farms and gardens can bring nutritious food (and its attendant public health benefits) back into “food deserts”—places where fast food chains are plentiful but fresh produce is rare and the nearest full-service grocery store may be inaccessible to residents without a car.

Community gardens, still growing in popularity, are increasingly seen as a valued use of land by municipalities and a worthwhile pursuit for residents interested in greening their neighborhoods and gaining food self-sufficiency. This is especially true in neighborhoods that have been hit hard by unemployment and economic disinvestment. Detroit is a case in point: the city’s unemployed and underemployed number near 50 percent, and approximately 30 percent of lots in the city are vacant. Community gardens are filling the void in neighborhoods and providing sustenance for residents struggling to get by.

Many believe that urban farming, especially market gardens and commercial farms, has the potential to foster entrepreneurship and spark economic and community development where more conventional development models have failed and outside investments are difficult to attract. Gardening in the city brings people out into yards and boulevards, strengthening relationships among communities and creating safer neighborhoods with more eyes on the street. Added green space creates a more aesthetically pleasing streetscape, but also provides habitat for native and beneficial animals and insects—including bees, which are critical to the health of ecosystems and provide yet another opportunity for urban farming entrepreneurs as well as backyard beekeepers. And above all, in-city farming can bring greater resilience to urban populations, which depend on fossil fuel-based systems for transporting critical resources—systems that by most accounts will be ever more vulnerable in a future of uncertain climate and resource availability.

Enough space?

Research shows thatthere is far more open land in American cities than one might think. A study by the Brookings Institution in 2000 looked at 70 major U.S. cities and found that an average of 15 percent of the land area within them was vacant. (These numbers are somewhat higher in the South and lower in the Northeast.) But with land values running prohibitively high in many of those cities—even those that have been hit hard by the recession—conventional models for agricultural land tenure simply don’t translate to the urban landscape. “You couldn’t do it if you had to pay a mortgage, especially if you want to pay a living wage,” says Ken Dunn, director and founder of Chicago’s City Farm, a project of the nonprofit Resource Center Chicago that grows vegetables for sale to restaurants and at farm stands on two acres within the city (and pays a living wage to its employees).

Many urban farms are the result of individually negotiated land-use agreements between farmers and landowners, often municipalities but also frequently private entities. These agreements allow farmers and gardeners to use the space without owning land outright, but often present barriers to longevity. City Farm has been at its current Chicago location—its fourth in 25 years—for six years, and the city says it may have to move again next year. “We put down roots lightly, so to speak,” Dunn says. “Instead of poles in concrete, the fences are stakes driven into the ground, all the more easily pulled up and used at the new site.” This flexibility can be a benefit, but can also discourage the kind of investment that can be necessary to start an operation like City Farm. Before growing food on a site, they grade and compact it, put down a layer of impermeable clay to block out underlying contaminants, and then bring in fresh, clean compost laid down two feet deep—no small investment at 1,000 tons per acre. But not all urban farms require such an investment, and even in a relatively economically vibrant city like Chicago, where farms must compete with other development interests (but which nonetheless has 20,000 acres of vacant land), the opportunities are there.

Recent developments show that city officials and planning departments are awakening to the benefits of integrating agriculture into the urban landscape. San Francisco Mayor Gavin Newsom recently ordered all city departments to conduct an audit of unused land, including vacant lots, windowsills, medians and rooftops, which could be converted into gardens. In Chicago, where Dunn has worked (sometimes with frustratingly little success) for decades to convince planners and city officials of the value of urban agriculture, City Farm will soon begin cultivating a new two-acre section on the city’s south side as part of a larger quality-of-life development plan for the surrounding neighborhood—a plan much like those Dunn had been proposing for nearly 20 years. “The studies indicate there’s likely no other demand for that space for the next 100 years,” Dunn says. “The city seems to see now that urban agriculture is an opportunity to have something vital going on there.”

Is urban soil fertile enough?

Finding ideal soil conditions for growing vegetables can present a variety of challenges in an urban environment. Previous land uses, especially former industrial sites, gas stations, and drycleaners, can leave soil contaminated with heavy metals or harmful chemical compounds—soil testing is a must. In areas where demolition has occurred, there may be concrete or other inorganic detritus present in soil.

“Most urban lots have what we some times call ‘urbanite,’ ” explains Brad Masi, executive director of the New Agrarian Center at Oberlin College in northeast Ohio, which leads the City Fresh initiative in nearby Cleveland. “It’s a unique urban soil—very compacted and full of rubble.” Urban farmers have devised plenty of ways to work with and around urbanite, however. One solution that has caught on in Cleveland and elsewhere is “asphalt gardening”—building raised beds directly on top of unused parking lot space and other paved surfaces. Through workshops hosted by the New Agrarian Center, Cleveland residents learn to fill strawbale- or cinderblock-framed beds with layers of cardboard, wood chips, shredded newspaper and office paper, discarded vegetable matter, and a smaller amount of prepared soil; then earthworms do the job of breaking down the constituents. The paved surfaces function as a reliable barrier between the beds and potential contamination in the soil beneath. “EPA studies looked at asphalt leaching and determined that it doesn’t cause any problems with contamination,” says Masi.

The availability of cheap and free soil-building elements for Cleveland’s asphalt gardens underscores a critical reality that gives cities one small edge over rural areas, at least on this point. “You’ll find there’s an abundance of material that can be composted,” Masi says. “Cities are really rich in that way.” Richard Pederson of City Farm in Providence, Rhode Island, (no connection to Chicago’s City Farm) makes the rounds of City Farm’s downtown neighborhood, collecting leaves from a nearby cemetery and organic waste from area businesses—cups and coffee grounds from a coffee shop, for example. It’s a good way to meet the neighbors and introduce them to the farm in their midst, he says. When asked about the fertility of urban areas, Pederson focuses on one number: “Twenty-five—that’s the percentage of trash going to the landfill that is biodegradable and could be used to build soil for urban farms and gardens.” It’s a resource he and others believe could be utilized much more productively.

On the ground techniques

Places like Providence’s City Farm show that, given the right approach, it’s possible to make market gardens and commercial urban farming operations viable with less space than you might think. Pederson, who was hired at City Farm eight years ago, introduced a variation on the “biointensive” method of farming that allows City Farm to sell vegetables to local restaurants and at three different local farmers markets, while still having leftovers to give to farm volunteers and neighbors—with just 5,000 square feet of their 3/4-acre lot dedicated to vegetable cultivation. Developed in the 1960s, biointensive methods focus on building soil while producing large yields from a relatively small land area. At City Farm this means double-digging the top two feet of soil to alleviate compaction and increase drainage, building permanent rounded beds with walkways to accommodate workers, and planting with particular spacing (depending on the plant), using a hexagonal rather than the more conventional row-based layout. They plant cover crops in the fall, another biointensive element, but unlike strict biointensive farms, which must grow all their soil inputs onsite, Pederson widens his closed-loop soil-building system to include organic material collected from the surrounding neighborhood. “The farm can support local businesses by buying or using these things that would otherwise go to the landfill,” he says.

Permaculture—a hybrid of the words “permanent” and “agriculture”—is another alternative agriculture method that has the potential to transform urban neighborhoods through the design of landscapes that integrate agricultural and human communities using systems that mirror natural processes. By definition, permaculture landscapes are often anchored by perennial crops, including fruit trees, and sustained by natural systems like onsite composting. A project called Pittsburgh Food Forests, begun in 2009 in a blighted section of Pittsburgh’s Hazelwood neighborhood, aims to establish permaculture landscapes throughout the city—“forests” with perennial fruit and nut crops and vertical layers of food production, including annual and perennial understory species, vines, and root crops growing near and underneath the food-producing trees. According to Juliette Jones, co-manager of the project, the goal is to train and involve members of the surrounding community in stewardship of the forests and share with them the fruits of the harvest—and ideally inspire people to create similar landscapes near their own homes.

Rooftops are also increasingly being seen as a “land” resource with farming potential. Green-roof systems, like those installed on many high-performance buildings to minimize the heat-island effect and mitigate stormwater runoff, are not commonly used to cultivate vegetable crops—mostly sedums or similar cover species. But container vegetable gardening on rooftops has a long history in urban areas, and many rooftop farmers are branching out into ever more extensive systems.

There are critical logistical challenges to be aware of with rooftop growing, however. Many roofs are not structurally sound enough to support the weight of heavy soil beds or greenhouse structures—a structural engineer should evaluate the integrity of any rooftop being considered for a larger-scale gardening installation. The edges of rooftops will generally be the areas best able to support moderate loads. Potential rooftop gardeners should also remember that all the necessary implements—including soil—will need to reach the roof somehow, and a rooftop without good building access may not be the best candidate for an extensive garden no matter how much weight it can support. When making the Down payment on a house, make sure you have the provision for a roof top garden.

Hydroponics, a method of cultivating plants in water and non-soil growing media, is an option where soil is unavailable, in greenhouses and even inside buildings. Proponents like hydroponics because of common claims that it is more productive, reliable, and water-efficient than growing outdoors in soil, while others dislike the dependence on chemicals, and some feel that the vegetables it produces have an unnatural taste. Aquaponics, a variation on recirculating hydroponics and aquaculture (fish farming), relies on natural relationships between the plants and the animals in the system, making it preferable to some who question the chemical nature of hydroponics. Aquaponics is mostly done on a noncommercial scale, but a Milwaukee company called Sweet Water Organics is taking the aquaponics model pioneered at the nearby educational farm Growing Power (the project of MacArthur “genius grant” recipient Will Allen) and attempting to make it commercially viable. In a converted, previously abandoned industrial building, three-tiered wetland pools contain perch and tilapia, whose waste provides nutrients for the rafts of greens growing hydroponically above the pools, while the plants in turn clean the water by absorbing the nutrients—solving the principal problems of both hydroponics and aquaculture.

The future of urban farming

Hypothetical scenarios of a future in which all food production will necessarily be local have prompted some to envision vast urban landscapes stacked with vertical acres of skyscraper farms—controlled, heavy-infrastructure (and capital-intensive) environments growing food crops indoors under conditions bearing little resemblance to anything that fits the current definition of a farm. But those solutions are far from being realized, and the optimism that exudes from urban farmers working in the current, more down-to-earth models suggests that the need for them may not arise. One statistic that many city farmers know and cite when asked whether cities have the capacity to feed themselves: During World War II, 40 percent of all the vegetables consumed in the United States were grown by citizen farmers in 20 million backyard “victory gardens.”

The Detroit-based organization Urban Farming has a clear and specific mission to address the needs of a hungry population: Their community garden plots are unfenced, with a help-yourself invitation to neighbors. When the group first got started five years ago, they usually donated 50 percent of the harvest that wasn’t taken by residents. More recently, in peak recession years, hungry neighbors have picked the gardens clean—which is all part of the plan. “When you’ve got a suffering community and a garden of fresh food, you don’t want to put a fence up,” says founder and executive director Taja Sevelle. “That’s not what we do.”