Photo credit: Bright Farms

Picture a metropolis adorned with hydroponic rooftops, each churning out tons of healthy, carbon-neutral food. A distant utopia? Not to Paul Lightfoot, CEO of Bright Farms, a New York City based greenhouse maker.

“Our mission is to increase the availability of locally grown produce nationwide,” Lightfoot said, outlining the company’s plan to convert a 100,000 square-foot roof of an unused Brooklyn warehouse into a sweeping food plantation. “Building the world’s largest rooftop farm is a huge step towards our goal.”

Hydroponic farming is a way to cultivate various crops in nutrient-rich water, without the use of soil. Atop roofs, this method of agronomy can yield extensive environmental benefits, including stormwater capture and recycling, pesticide-free food, and far less fuel needed to transport it to local markets.

A growing number of farming companies, including Brooklyn Grange, have followed suit with rooftop projects of similar size and scale. But how much resources does it take to reimagine the hanging gardens of Babylon and use them to feed a major American city? Too much, says Regina Akerman Morrow, who runs Crest Hardware & Urban Garden Center in Williamsburg, just a few miles from the planned rooftop mega-farm.

“We have discussed carrying hydro supplies at work, but opted not to,” Akerman Morrow said, explaining that using water instead of soil is “a very clinical, and extremely expensive endeavor.”

“I firmly believe that even if we supply all the nutrients, microorganisms and known elements to food crops, we won’t achieve the same results,” she said. “I don’t think we know all there is to know about soil yet.”

In addition to warding off waterborne bacteria and investing in advance control and monitoring systems, leasing industrial rooftop space involves complicated agreements with zoning boards and powerful real estate interests. This leaves small urban gardeners like Akerman Morrow, who remains cautiously optimistic about hydroponic rooftops, on the other side of the red tape.

“After good 10 years of working farms, data, and fed people, rooftop farming could be a legitimate, sustainable method of getting fresh food to cities,” Akerman Morrow said. “The process, on the other hand, seems like it takes all the fun out of growing things.”