The Atlantic: Urban farming reaches new heights in the latest video from The Perennial Plate, a web series about sustainable food. This episode introduces Osbert Lam at City Farm in Hong Kong and Guichun Zhang in Beijing, who have created leafy green escapes among the high rises of their respective cities. Beijing has over 90 million square miles of empty rooftops, Zhang says, and Daniel Klein and Mirra Fine, creators of the series, say urban gardening has become "a burgeoning movement" in China. The New York Times attributes the trend in Hong Kong in part to a desire for organic produce and a distrust of farming methods in mainland China. The Perennial Plate's video seems to suggest that above all, gardening is just a pleasure; Zhang takes visible delight in his vegetable patch and Lam says, "it's relaxing hobby, growing something. It's like a tranquilizer for city people."