Species Native to Missouri
Common Name: Carolina larkspur
Type: Herbaceous perennial
Family: Ranunculaceae
Native Range: North America
Zone: 4 to 7
Height: 1.00 to 2.00 feet
Spread: 0.75 to 1.50 feet
Bloom Time: April to June
Bloom Description: Blue-violet
Sun: Full sun to part shade
Water: Medium
Maintenance: Medium
Flower: Showy
Attracts: Hummingbirds, Butterflies
Tolerate: Rabbit, Deer
Culture
Winter hardy to USDA Zone 4 where this delphinium is best grown in fertile, humus rich, medium moisture, well-drained soils in full sun. Performs well in alkaline soils. Appreciates some part afternoon sun-dappled shade in hot summer climates. Prefers climates with cool summer temperatures. Plants sometimes struggle in St. Louis summers, and are 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.
Noteworthy Characteristics
Delphinium carolinianum, commonly known as wild larkspur or Carolina larkspur, is an herbaceous perennial of the buttercup family that is native from Virginia to Missouri south to Florida and Texas. It is native to moist rich woods, thickets, ravines, hill prairies, upland sand prairies, rocky limestone glades, barren savannas, upland rocky woodlands, wooded rocky slopes, dry open woods and railroad right-of-ways. It grows within the same geographic range as D. tricome, but is basically a taller and later blooming relative. It is variable in terms of flower color, stem pubescence, plant vigor and leaf size.
Each plant features a basal cluster of long-petioled, grayish-green leaves (to 4” wide), each leaf being palmately cleft into five deeply cut lobes with each lobe being further divided into 2-3 secondary 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 rising from the basal leaf cluster in an April-May bloom which occurs at a time 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 five petal-like sepals and four 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.
Genus name comes from the Greek word delphis meaning dolphin in reference to the flower bud shape of some species purportedly resembling a dolphin.
Specific epithet means from Carolina in reference to habitat.
Problems
Delphiniums require considerable maintenance (staking, pruning, deadheading, disease control) in order to perform well in the garden. Delphiniums are generally susceptible to powdery mildew, botrytis blight, leaf spots and crown rot. 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. Watch for aphids, leaf miners, stem borers and mites. Taller plants may need staking, and appreciate being sited in locations protected from wind. Plants are considered toxic to humans if ingested.
Uses
Superb in cottage gardens. Beds and borders. Best in groupings or massed. Plant against a stockade fence for protection from wind. Excellent cut flower.