As cities expand, eating up swathes of countryside in the process, agricultural pioneers are finding new ways to grow the fresh produce we need, in containers, empty buildings and any other spare space they can find to create new vertical farms. “We are just trying to imitate nature. It’s not as futuristic as it might sound,” insists a smiling Maarten Vandecruys, the youthful founder of Urban Crops, a new Belgian company specialising in indoor growing…