Celebrate the start of summer with a visit to Chelsea in Bloom, Chelsea’s prestigious annual floral art show and London’s largest free-to-attend festival of flowers. What is Chelsea in Bloom? The world class alternative floral art show is back for its 20th anniversary, transforming the streets of Chelsea from 19-25 May, with breathtaking displays made of fresh flowers. Produced by Cadogan, in association with the Royal Horticultural Society (RHS), the annual competition continues to grow year on year, with Chelsea’s best retailers, restaurants and hotels adorning themselves with creative designs, competing for the coveted awards.