It's harvest time, but not as we know it, as Matt Baker and Charlotte Smith visit a farm in Cambridgeshire growing something rather unusual for the UK. Charlotte meets pioneering farmer David Mwanaka, who raises crops from his native Zimbabwe. It's not the first time they have met. Eleven years ago, Charlotte interviewed him for a radio show on a plot of land in north London and admits she thought David's dream of African crops in the UK was not going to succeed. She couldn't have been more wrong. Today, David farms 485 acres of rare crops, including his favourite and most successful white maize. Charlotte catches up with David on a tour of his new farm, where they reminisce about their first meeting and how his dream of growing native African fruit and veg has become a reality, despite many setbacks. Matt meets David in his eight-foot-high white maize crop to help at a critical time in their harvest, and Matt and Charlotte join the family for a well-earned feast fresh from the farm. A few miles away, we visit a community farm trying its hand at growing some rare crops, including oca and quinoa. Adam Henson is in Cornwall helping out with a tea harvest.