Skies of Lettuce: Rooftop Greenhouses Sprout in Big Cities

Growing food in greenhouses on rooftops was not only feasible on a commercial scale, it was also an adaptive use of urban space that’s environmentally friendly, according to co-founder and CEO of Gotham Greens

Viraj Puri didn’t have much of a green thumb seven years ago. Now he runs a company that produces 20 million heads of lettuce a year.

Puri is the co-founder and CEO of Gotham Greens, a company that grows basil, bok choy, arugula, kale and other leafy greens in its rooftop greenhouses in New York City and Chicago.

"I came from an environmental engineering background, not a farming or food background," Puri told NBC. 

He realized his Gotham Greens concept was a viable idea after working in a greenhouse. Winning the New York City Green Business Competition in 2011 cemented his vision. Growing food in greenhouses on rooftops was not only feasible on a commercial scale, it was also an adaptive use of urban space that’s environmentally friendly, he explained. 

City farming itself is nothing new. Roughly 800 million people worldwide practice urban agriculture, according to the Food and Agriculture Organization of the United Nations. But growing interest in locally-grown produce in recent years has fueled creative city farming techniques, like vertical farms and community gardens, as well as the relatively new method of rooftop greenhouses. 

Puri co-founded Gotham Greens in 2009 with partner Eric Haley in response to “this growing trend in the market place in local, transparent, and sustainably produced food.” The company claims it is the largest urban agriculture company in the world and that it has experienced 400 percent growth in the past year with the opening of its Chicago greenhouse in October 2015.

His greenhouse in Chicago's South Side, which sits atop a soap factory and measures 75,000 square feet, churns out nearly 25 crops of leafy greens per year, Puri said in an interview with The Associated Press. In comparison, a conventional farm in the region produces two to four crops, he said. 

Gotham Greens uses alternative farming methods, like hydroponics, which means the leafy greens are grown without soil. Instead, mineral solution and water, which recirculates throughout the greenhouse, nourish the plants. The greenhouses also rely on sunlight and are fully powered by renewable electricity, which allows the company to grow their greens year-round.

"We have heat curtains as part of the greenhouse and we pull them at night and that reduces the volume of air we're heating and that is really a low energy demand for us us, surprisingly," Chief Agriculture Officer Jennifer Nelkin Frymark told the AP.

A major tenant of Gotham Greens business model is its focus on local delivery. Produce is traditionally shipped to stores from California's Central Valley and from Mexico, and arrives in the Midwest and East Coast after several days. Gotham Greens' lettuce arrives in local stores and restaurants just hours after being picked. This not only extends the shelf life of the product, but also minimizes the carbon emissions, Puri told NBC.

"How often do you go to a restaurant and talk about their lettuce?" John Damas, general manager of Chicago restaurant LUXBAR told the AP. "It's kind of strange, but to be able to cut down lettuce and harvest it by hand and have it delivered and on the plate within hours is a huge deal."

Gotham Greens also reduces waste by giving any produce that does not meet grocery store standards to food banks, where it is then distributed to shelters and nonprofits.

In New York, Gotham Greens operates three greenhouses, including one that sits atop Whole Foods in Brooklyn's Gowanus neighborhood. The store's spokesperson Michael Sinatra said the partnership has been a “winning relationship” since both companies focus on reducing the carbon monoxide foot print in food deliveries and turning “food miles into food steps.”

Puri said his company is the only one successfully using the rooftop greenhouse model on a commercial scale. But, he said, “it’s becoming more popular and you are seeing more urban farming start up concepts overall.”

One place greenhouses are also popping up is in schools. New York Sun Works, a nonprofit, is teaching urban agriculture and has installed two rooftop greenhouses on city schools. 

“It really is a new way of teaching science through the lens of urban agriculture,” said Sidsel Robards, director of development and events for Sun Works. “If we all grow the food right here in the city, what would that do to traffic patterns, population, contamination?"

Sun Works has a total of 30 sites in schools to teach urban farming to students and teachers, but the schools often opt to turn a classroom into a “classroom farm” rather than the rooftop greenhouse because of the high cost, according to Robards. A school has to get a permit and build the greenhouse, a process that can take two to four years and cost upwards of $1 million.

While greenhouses serve a vital option in urban farming, Puri is the first to note this method has its limits. 

“I think Gotham Greens' climate controlled green houses can play a role in the future of farming, but I don’t think on its own it's the future of urban farming because it can only produce certain kinds of crops," he said. "It can't do grains, it can't do dairy, or protein."

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