Michigan State University Extension
Ornamental Plants plus Version 2.0 - 00000499
01/01/98
Hardiness Zones: 3 to 7 Height: 8 ft Spread: 2 ft Type: herbaceous perennial Flowers: Blue, pink, purple, white
Comments: Delphiniums are tall plants capable of reaching a height of 8 feet although most garden plants will be shorter. Delphiniums prefer a fertile, deeply prepared, well-drained soil and exposure to full sun. Remove the first flower shoot as it fades to obtain late season bloom. The plants send out new shoots and remain in flower for some time. Regular watering and fertilizing is needed. Apply no fertilizer later than August. Stake the spikes before the flowers open to prevent injury while the spikes are elongating. A check in growth, early in the season, causes widely spaced florets on the spikes. Winter protection is suggested. The plant lives longer in cool climates.
Propagation: Propagation is by seed, division and cuttings. Softwood cuttings can be taken in spring. The plants will not divide well. The seed germinates in 2 to 3 weeks at temperatures between 70 and 80 degrees. Darkness is necessary for germination.
Cultivars: Not all of the cultivars listed are D. elatum.
Other species or hybrids included in the list are D. X
belladonna and D. grandiflorum.
'Astolat' (Pacific Giant Hybrid) - Pink to rose colored
flowers with brown to black bees, the plants grow to
6 feet.
'Black Knight' (Pacific Giant Hybrid) - Dark violet
flowers with a darker bee, up to 6 feet tall.
'Blue Bird' (Pacific Giant Hybrid) - Clear blue with a
white bee, up to 6 feet tall.
'Blue Jay' - Blue flowers with white bees, about 5 feet
tall.
'Blue Springs' - Flowers in shades of lavender and blue
are produced on 30-inch tall plants.
'Connecticut Yankee Series' - The plants are about 30
inches tall and the flower colors are mixed.
'Galahad' (Pacific Giant Hybrid) - White flower, plants
up to 6 feet tall.
'Guinevere' (Pacific Giant Hybrid) - Pinkish lavender
flowers with a white bee, up to 6 feet tall.
'King Arthur' - Violet flowers with a white bee, plants
up to 6 feet tall.
'Magic Fountain' - A mixture of blue, white or violet
flowers, does not need staking.
'Pennant' - Two-foot tall plants in mixed colors that
included pink, creamy white, lavender and blue.
'Round Table Mixed' (Pacific Giant Hybrids) - A mixture
of colors, plants up to 6 feet tall.
'Summer Skies' - Light blue flowers with a white bee,
up to 6 feet tall.
References for Cultivars: Walters Gardens 1997, Ray Wiegand's Nursery 1995, Bailey Nurseries 1997, White Flower Farm 1997, Wayside Gardens 1996, Ray Wiegand's Nursery 1997. Lowell C. Ewart, 1997 Flower Seed Trials, Michigan State University.