Sean Gallup/Getty ImagesOnce, the roof was silver tar, sticky and blinding in the summer heat like a melting spaceship. Now, it’s a green oasis three stories above the ground. Annie Novak hunches over rows of crops, harvesting chard and arugula as she looks out over empty rooftops towards the Chrysler Building, the East River, and the water towers and smokestacks of derelict industrial plants. Her garden, Eagle Street Rooftop Farm, is a 6,000-square-foot for-profit operation atop a soundstage in Greenpoint, Brooklyn. Novak’s model—the sprawling, elevated farm with dozens of varieties of produce, plus bees, chickens, and rabbits—won’t work for everyone.