Rooftop farms have sprung up so quickly in American cities over the past decade that even the U.S. Department of Agriculture doesn’t know precisely how many exist.

Chicago is home to many, and New York City is a hotbed, of course, where places like Brooklyn’s Eagle Street Rooftop Farm (pictured above) provide fresh produce to neighborhood markets, and educational and volunteer opportunities for people itching to flex their green thumbs.

Few could argue that these spots have any downsides. They provide a pop of green to the concrete landscapes that surround them, and they encourage healthy eating. But as nice as community-building and locally sourced kale are, does gardening inside city limits actually put more food in more mouths?

The answer is probably no.