Could our office, apartment and public buildings also be farms? In this programme, Ruth Alexander meets the pioneers of rooftop farming, turning concrete into green spaces where fruit and vegetables are grown. We find out about the logistics, the challenges, and whether it has the potential to feed city populations. In Barcelona, Spain, she meets Joan Carulla, who recently celebrated his 100th birthday. Joan has been tending his private rooftop vegetable garden for fifty years with the help of his son, Toni. They’re joined by friend and fellow rooftop gardener, Robert Strauss. Ruth speaks to Kotchakorn Voraakhom, a landscape architect in Bangkok, Thailand. She designed a farm on the roof of a university in 2019, the largest in Asia at that time. And Mohamed Hage, co-founder and CEO of Lufa Farms in Montreal, Canada explains how they are farming rooftops on a commercial scale. To date the company has four rooftop greenhouses and an indoor farm, which produces enough food to feed about 2 per cent of the city’s population. Presented by Ruth Alexander. Produced by Beatrice Pickup. (Image: Joan Carulla sat on a bench in his rooftop garden in Barcelona, Spain. Credit: BBC)