Dahlia alba

Dahlia imperialis f. alba is the white-flowered form of the tree dahlia, native, like the type species, to the mountains of Mexico and Central America. It shares the giant habit and hollow, bamboo-like stems of Dahlia imperialis, reaching over 4 m tall, but is distinguished by its large, pendulous, pure white flowers with yellow centres, produced in late autumn. Grow in a sheltered spot in rich, moist soil and full sun; the rootstock needs winter protection in cold climates.