Girl visitor to the RHS Chelsea Flower Show make her way home through Sloane Square after the last day's plant sell-off. A yoiung woman walks through a Chelsea street laden with an armful of flowers on the show's last day. The RHS Chelsea Flower Show, formally known as the Great Spring Show, is a garden show held for five days in May by the Royal Horticultural Society (RHS) in the grounds of the Royal Hospital Chelsea in Chelsea, London. The show is the most famous flower show in the United Kingdom, perhaps the world attracting visitors from all over the world to see this annual festival of innovative garden design themes and the most perfect of plants presented during the week in May every year.