Delphinium

Delphinium is a genus of herbaceous, flowering plants containing more then 500 species. These native species, commonly called Larkspurs, include annuals, biennials, and perennials and can often be found growing wild in forests or natural areas in rich woods and in mountains. Some spread in disturbed areas in woods and fields and can become weedy in gardens. Most of the plants sold today are complex hybrids although the Larkspur species that return from seed or perennial rootstocks every year perform much better in the warm gardens of the South than the hybrid Delphiniums. The genus name comes from the Greek word delphis meaning dolphin in reference to the flower bud shape of some species resembling a dolphin.

Delphinium do best in fertile, medium moisture, well-drained soils in full sun and tolerates alkaline soils. The plant prefers cool summers, but will do well if protected with afternoon shade in hot summer climates. It can be a challenge to grow them in humid summer climates south of USDA Zone 7. Delphiniums require considerable maintenance (staking, pruning, deadheading, disease control) in order to perform well in the garden. Plants, especially taller varieties, require protection from strong winds and rain storms by means of shelter and staking. After bloom, promptly cut back spent flowers to the basal foliage for additional late summer and fall blooms.

Diseases, Insect Pests, and Other Plant Problems:

Susceptible to powdery mildew, botrytis blight, leaf spots and crown rot. Plants 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.