delphinium

Delphinium is a genus of flowering plants in the family Ranunculaceae, commonly known as delphiniums or larkspurs. The genus comprises roughly 300 species native to temperate regions of the Northern Hemisphere, with a strong presence in Europe, Asia, and western North America. Delphiniums are popular ornamental plants, valued for tall, brightly colored flower spikes and long-lasting blooms. All parts of the plant are poisonous if ingested, containing diterpenoid alkaloids.

Most delphiniums are herbaceous perennials or annuals that grow as upright clumps or tall stems reaching from 0.5 to over 2 meters, depending on cultivar. Leaves are palmately divided. The flowers appear in tall racemes with densely packed individual flowers; typical colors range blue, purple, and indigo, but pink, white, and rarely yellow forms exist. The bloom period is late spring to early summer in temperate climates, with best form in cool conditions.

Gardeners value delphiniums for architecture in borders, but they require well-drained, fertile soil and full sun to light shade. They prefer cool roots and may struggle in hot, humid areas. Staking is often necessary to support tall flower spikes. Regular feeding with a balanced fertilizer promotes strong growth; remove spent flowers to encourage rebloom and better appearance. They dislike root disturbance; divide infrequently. Many hybrids are developed from Delphinium elatum and other species.

All parts contain toxic alkaloids and can cause serious symptoms if ingested by humans or animals; wear gloves when handling. They are susceptible to powdery mildew, leaf spot, and stem rot in damp conditions, and can suffer from aphids and slugs. They attract pollinators such as bees and butterflies. In horticulture, delphiniums are often propagated by seed or by division of mature clumps.