Delphiniums bring to mind the vision of tall spikes of blue flowers in the background of the English perennial border and old fashioned cottage garden. The modern delphinium is a result of hybridization of delphinium species from many parts of the world.
A member of the buttercup (Ranunculaceae) family, delphinium consists of around 250 species of annuals, biennials, and perennials. Delphinium comes from the Greek word for dolphin, a reference to the new flower bud's resemblance to the bottle-like nose of the dolphin.
In Tudor England some of the species grown were referred to as "larkspur" apparently because the nectar sepal looked somewhat akin to a lark's claw. The common name larkspur also applies to a similar looking but different plant called Consolida ajacis.
Delphinium flowers may be single or double. Blue is the most common color; however, red, pink, white, violet, and yellow flowered species and varieties also are available. Many flowers have white or black centers known as "bees."
Flowers occur in regal spikes with numerous flowers on each spike. The spikes of most delphiniums make attractive, long-lasting cut flowers. The foliage is palmately lobed and is divided into 3 to 7 parts depending upon the location on the stem.
Mature plants can reach 6 to 9 feet tall, though dwarf varieties grow 3 to 4 feet tall. Placing the tall plants in the background of a perennial bed is one popular choice. Delphiniums can also be used as specimen plants or as a small grouping in the garden.
Some Delphiniums you can expect to find at Portland Nursery:
D. elatum 'Chocolate': Tall graceful spikes are filled with highly varied flowers in blends of velvety deep brown, lighter cocoa, and ivory, each bloom uniquely veined, picoteed, or stippled, with even an occasional cherry-pink or blue undertone. Bees range from deep, dark near-black to striped brown-and-white to bright minty green. The overall effect of the Chocolate Delphinium is a vision of sweet creamy white chocolate with smooth milk and rich dark chocolate swirled throughout.
D. elatum Guardian Series:
A Pacific Giant hybrid that grows 24 to 36 inches tall and wide. There are several varieties in this series with shades of blue, lavender, white, and mix shades.
D. elatum 'Magic Fountain Mix':
Bushy plants are 3 feet tall and 2 feet wide with blue, lilac and white flowers in June. Well suited for windy areas.
D. elatum New Millennium Series:
An English hybrid bred for exceptional garden performance. Sturdy, strong-stemmed spikes packed with loads of richly colored flowers, often double or semidouble that can rebloom during a single season. 6 feet tall and 2 feet wide. Some varieties include 'Blue Lace,' 'Green Twist,' 'Pagan Purples,' and 'Sweethearts.'
D. elatum Pacific Giant Hybrids:
Stately plants with tall regal stalks and spikes of semi-double blue, lavender, pink, white and bi-color florets can reach a height of 4 to 6 feet and can rebloom in a single season. Several varieties include 'Pacific Giant Mix,' 'Galahad,' 'Guinevere,' 'Black Knight,' and 'King Arthur.'
D. nudicaule 'DeRosso Red' (Red Delphinium):
Vibrant flowers in a most unusual color for delphiniums are irresistible to hummingbirds and butterflies. Compact, bushy plants are 10 to 14 inches and bloom in May. Beautiful at a garden's edge, rock gardens or in patio containers.
Common Name: Larkspur
Origin: Northern Hemisphere, with many species native to the western United States.
Culture: Site plants in a location that receives at least six full hours of sun and is protected from the wind. Plant in well-drained soil amended with organic matter. Plant them at least two feet apart.
This herbaceous perennial is very hardy and tolerant of frosts. It dies to the ground in the winter and wakes up early in March. Delphiniums are short-lived perennials. They often need to be replaced every 2 to 3 years, especially when planted in heavy soils.
Maintenance: Most hybrids flower early to mid summer. Immediately after flowering, remove the flower stalk. Cut off the spikes under the first bottom floret on the spike and allow the green stems and the foliage to die down naturally. This will encourage additional flower spikes in late summer or early fall. Thinning is essential for delphiniums. First year seedlings should have only one flower spike.
Second year plants should only be permitted to have three flower spikes. Older and established delphiniums should be permitted to have only five flower spikes. Staking is helpful for delphiniums. The correct method of staking is to contain the stems of the plant, not the flower spike.
These heavy feeders appreciate soil rich in compost, well-rotted manure, and regular use of a balanced 10-10-10 fertilizer. During the growing season they require deep watering at regular intervals. Mulching around plants will keep their roots moist and cool.
Pest & Disease: Slugs can be problematic in the cool wet spring as plants break dormancy. "Sluggo" is organic slug control bait. To prevent powdery mildew and black spot place plants in an open airy position to promote circulation. To control powdery mildew and black spot use an organic fungicide with sulfur. Waterlogged soils in the winter will cause the crown to rot and that is why excellent drainage is absolutely necessary.
A common condition known as "blacks" (caused by cyclamen mites), results in stunted and deformed plants and buds that turn black. Practice good sanitation by removing and destroying infected and infested plant debris.