A look at the German garden island of Mainau in Lake Constance, visiting the Dahlia Garden, where an astounding 12,000 flowers bloom across 280 varieties. Also featured are 3D floral installations, including a giant peacock, an innovative 1,700 square metre rooftop garden teeming with more than 16,000 plants representing more than 300 species, and one of Europe's largest butterfly houses.