This episode is the first of two visits to the RHS Flower Show at Tatton Park in Cheshire as it celebrates its 20th birthday with a festival of flowers. The team of horticultural experts explore the diverse range of show gardens, including the compact 'back to backs' category - exclusive to the show - and we tour the floral marquee to discover the plants that give our gardens the scent of summer. The show meets the first three of the five fresh-faced designers who have secured their place in the 10th annual RHS Young Designer of the Year competition, and discovers the darker side of plants in a new exhibit - the Poison Garden.