Siberian Larkspur is a free-branching perennial that brings gentian-blue spires of intricate, asymmetrical flowers to the early summer garden from June through July. This delphinium grows 12 to 24 inches tall and thrives in hardiness zones 4 to 7, making it accessible to most northern gardeners. The plant's complex, spurred flowers are excellent for cutting, and the foliage is finely divided and elegant, creating a light, airy presence in the border. Unlike many delphinium hybrids, it tolerates heat better and handles frost reliably, though it's often short-lived and frequently grown as a biennial or annual.
Full Sun
Moderate
4-7
24in H x 18in W
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High
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The distinctive spurred flowers give this larkspur its name: each bloom features five sepals, one of which extends into a characteristic prong that seems to dart forward like a lark in flight. Butterflies visit the blooms reliably, and deer leave the plant untouched, making it a dependable choice for wildlife gardens where protection from grazing matters. Its loose, branching habit and long stems provide exceptional cut flowers, rewarding you with armfuls of blue for the vase.
Siberian Larkspur is grown primarily as an ornamental flower for the summer border and for cutting. The showy blue spikes work beautifully in fresh arrangements, and their height and branching habit make them valuable for creating vertical interest in garden beds and bouquets.
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Start seeds indoors 6 to 8 weeks before your last spring frost. Sow at a soil temperature of 55 to 70°F. Press seeds lightly into soil; they need light to germinate, so do not bury them deeply. Keep soil consistently moist and cool during germination.
Harden off seedlings over 7 to 10 days before transplanting outdoors after your last frost date. Space plants 12 to 18 inches apart in their final position. Transplant when soil has warmed and frost risk has passed. Handle gently, as larkspur seedlings are somewhat brittle.
Direct sow seeds outdoors in spring after the last frost, or in autumn in warmer zones for overwintering and spring bloom. Press seeds into prepared soil without burying them. Keep soil moist until germination occurs.
For cut flowers, harvest spikes in the morning when the first flowers on the raceme are just opening; they will continue to open as they sit in the vase. Cut stems above a set of leaves to encourage branching from that point.
Remove spent flower spikes after bloom to encourage continued flowering and a possible second flush of blooms in autumn. Deadheading extends the display and prevents excessive self-seeding. In late autumn or early spring, cut back any remaining foliage to the basal growth.
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