Japanese firm prepares to start world’s largest vertical farm. : In a suburb of Kyoto in Japan, surrounded by technology companies and startups, Spread Co. is preparing to open the world's largest automated leaf-vegetable factory. It's the company's second vertical farm and could mark a turning point for vertical farming - bringing the cost low enough to compete with traditional farms on a large scale. For decades, vertical farms that grow produce indoors without soil in stacked racks have been touted as a solution to rising food demand in the world's expanding cities.