For our latest episode of Built in Brooklyn, we went to the new Whole Foods in Gowanus — which might seem a little strange, but that’s where you’ll find urban agriculture startup Gotham Greens.

Specifically, the company runs a greenhouse growing pesticide-free produce on the store’s roof, and that produce is sold in the Whole Foods itself. (To be clear, Gotham Greens has three rooftop farms/greenhouses in New York City, and it has plans to expand elsewhere. Its produce isn’t just sold in Whole Foods, either.)

But why grow on rooftops at all? Co-founder and CEO Viraj Puri pitched this kind of agriculture as part of a broader trend of new, sustainable farming methods.

“In cities we don’t have a lot of arable land. We don’t have a lot of fertile soil. But one vastly udnerutilized resource we do have is unused rooftop space,” he said. “The idea was to take this otherwise unused space, turn it into productive space where we could grow year-round, high-quality product for local customers.”

Puri, along with his co-founder Eric Haley and the company’s chief agricultural officer Jennifer Nelkin Frymark, walked us through the company’s story, outlined the company’s farming methods, and showed us the greenhouse itself, and that’s all in the video above.