Chickens are coming home to roost in U.S. cities, near pens for goats and hives for bees. In urban yards and on once-vacant lots, planting beds brim with herb plants, pea vines, and the ubiquitous kale.

A new wave of urban agriculture is flourishing because it benefits consumers concerned about sustainably grown food as well as cities with land to spare. It started in 2008, fueled both by economic stress and concerns about nutrition, childhood obesity, and diabetes highlighted by First Lady Michelle Obama.

"There's been tremendous growth in the number of urban farms in cities dealing with an excess of land and not enough people living [there]," said Anne Palmer of the Center for a Livable Future at the Johns Hopkins Bloomberg School of Public Health in Baltimore, and in "any city where land is somewhat undervalued."

That's one reason Baltimore and Detroit are hot spots. But beekeepers and community gardens are also proliferating in upscale neighborhoods, where there are long waiting lists of foodies and locavores for garden plots.

Madison, Wisconsin, which last year issued 197 poultry permits, has already issued 178 for this year (with the year half over).

Urban farming by definition keeps food production local. That reduces energy use and other costs of food transport, and brings more healthy, fresh foods to neighborhoods where they historically have been scarce—the so-called food deserts.

"Equal Access"

In Milwaukee, Will Allen founded the nonprofit Growing Power to provide "equal access to high-quality safe and affordable food to people in all communities." Allen, a former professional basketball player and farmer whose parents were sharecroppers, was awarded a MacArthur Foundation "genius grant" in 2008 for his farming endeavors.

Growing Power grows produce and raises livestock at locations in and near Milwaukee, Madison, and Chicago. Its products are sold to local restaurants, at area farmers markets, and at the nonprofit's own café in one of Milwaukee's food deserts. The collective's other ventures include composting—to create the soil it uses—and aquaponics, which uses waste produced by farmed fish to produce nutrients for plants and then reuses the filtered water.

"We grow food," said Growing Power's Tami Hughes, "and we grow farmers."

Healthy Foods for Urbanites

In the nation's capital, the University of the District of Columbia has worked closely with the city government to encourage availability of healthy foods and sustainable food production—growing plants, composting plant waste, and growing more plants with that compost.

Sabine O'Hara, the dean of UDC's College of Agriculture, Urban Sustainability, and Environmental Science, says the school is now integrating its land-grant and academic programs more closely. (UDC is a land-grant university, a federally established category of colleges and universities created in the 1800s to teach "agriculture and the mechanic arts.")

UDC has a farm in Beltsville, Maryland, near the U.S. Department of Agriculture's Agricultural Research Center, with 25 acres under cultivation and plots where, says O'Hara, "we show what can be grown and different growing methods."

Some food is donated to nonprofits for the city's hungry, but the university also has a contract with the Hay-Adams Hotel near the White House.

"We grow food that is high in quality and high in nutrient density," said O'Hara, who has a doctorate in environmental economics and a master's in agricultural economics.

UDC is also trying to bring healthy, fresh food to consumers who may not have had access to it. Two chefs on staff can provide recipes and samples of how to prepare the fresh offerings at the city's farmers markets. And UDC has received a grant from the District's Sustainable D.C. initiative to help finance a food truck, which O'Hara says would be another way to fertilize food deserts.

Another goal is creating jobs, perhaps in growing specialty crops for Washington's many ethnic communities—one of the concepts UDC is demonstrating at its Beltsville farm.

Cash Crops

While urban agriculture is often an individual, family, community, or nonprofit venture, Big City Farms in Baltimore is a business—and it hopes, eventually, to be a profitable one. Chief Executive Dave Bisson said the for-profit venture aims not just to educate the public about food issues, "but also to make a substantial dent in the supply, replacing supplies coming from other parts of the country or other countries."

It also hopes to eventually be 100 percent employee-owned, and to provide year-round, full-time employment for more than its current nine full-time workers.

Big City Farms is farming on a handful of lots as small as half an acre and is using a 40-foot shipping container fitted with sinks and refrigeration to clean and store produce. Its West Baltimore site is a "network farm" with the nonprofit Strength to Love II, which employs an additional three workers.

"Big City Farms supplies the expertise and pledges to purchase everything grown there and prepare it for market," said Bisson.

Hurdles to Clear

Impediments to urban agriculture include contaminated or compacted soil. Sometimes the answer is to import soil from elsewhere. Growers should research a site's history and test the soil, said Johns Hopkins's Palmer. Also, empty lots where growers have spent years building up the soil may suddenly be attractive for other uses. Goodbye, farm.

And those chickens? Although many cities—including Philadelphia, Los Angeles, and Dallas—allow them, ordinances vary on how far away from neighboring buildings they must be kept, or how often manure has to be cleaned.

But no roosters need intrude on urban sleep: They're necessary only for fertilizing eggs, not for laying them.