Alan Titchmarsh and Joe Swift celebrate Chelsea's horticultural heroes in a second extended special from the Royal Hospital Grounds. Alan meets the Australian nursery who are recreating the voyage of plant hunter Sir Joseph Banks in a plant-packed show garden. Modern-day plant collector Tom Hart Dyke joins the team to seek out some of his favourite floral exhibits in the Great Pavilion, and writer and broadcaster John Humphrys joins Alan to talk about a passion for gardening which started when he was a teenager.