This plant will make a definite statement in your shade garden. Stunning purple color.
Delphinium tricorne is winter hardy in USDA Zones 4-7 where this delphinium is best grown in fertile, humus rich, medium moisture, well-drained soils in full sun. It also performs well in alkaline soils. Afternoon sun-dappled shade is beneficial in hot summer climates. Prefers climates with cool summer temperatures. The species is generally not recommended for growing in hot and humid summer climates south of USDA Zone 7. Plants are best grown in areas protected from strong winds and rain storms. Plants may be grown from seed and may self-seed in the garden.
Delphinium tricorne, commonly known as dwarf larkspur, is an herbaceous perennial of the buttercup family that is native to moist rich woods, thickets, ravines, wooded rocky slopes, and cliffs from Pennsylvania to Minnesota south to Oklahoma and Georgia. Each plant features a basal cluster of long petioled grayish-green leaves (to 4” wide), each leaf being palmately cleft into 5 deeply cut lobes with each lobe being further divided into 2-3 secondary lobes (or deeply palmately cut into into narrow lobes). A sparsely-leaved flowering stalk clad with small alternate leaves and topped by a stately terminal spire typically containing 6-14 blue-violet spurred flowers rises from the basal leaf cluster in an April-May bloom which occurs at a tune when the flower stalk has risen to about 12” tall. Plants continue to grow upward after bloom, eventually reaching 18-24” tall. Each flower (to 1 1/2” long) has 5 petal-like sepals and 4 petals. Sepals are usually violet blue to purple, but sometimes variegated with white. The upper sepal of each flower forms a long upright backward projecting spur as described by the common name of larkspur. The four petals are very small. Fruit is a seedpod which separates into 3 parts, with the dried ends extending upward in a manner reminiscent of horns.
Delphiniums can require some maintenance (staking, pruning) in order to perform well in your garden. Plants grown in full sun generally show better resistance to powdery mildew. Water plants at the base to avoid wetting the foliage. Crown rot will inevitably develop if plants are grown in poorly drained soils or planted too deep. Slugs and snails can do significant damage. Taller plants may need staking and appreciate being sited in locations protected from wind. Plants are considered toxic to humans if ingested.
This is a superb plant for cottage gardens, beds and borders. Best in groupings or massed. Plant against a stockade fence for protection from wind. Excellent cut flower.
Adapted from : Missouri Botanic Garden