The "Delphinium Giant Imperial" cultivar produces 4-foot, cone-shaped spikes of double blue, pink and white flowers over feathery green foliage. "Giant Imperial," needs full sun and well-drained soil so root rot doesn't stop the plant's summer-long bloom. "Giant Imperial" is an ideal choice for climates with cool summers and blooms begin in early summer when started from seed.
Zones 3-10.