By Sarah Browning, Nebraska Extension Educator
There is no other flower that creates the feeling of an “English” or cottage garden, more than delphiniums. Delphiniums are majestic plants with their long, colorful flower spikes making spectacular additions to a perennial garden.
The name delphinium is derived from the Greek word delphis, which refers to the dolphin-shaped flower buds before they open. Flowers are usually blue, but also come in white, pink, red, violet, and purple. The common name larkspur comes from the shape of the flower, which resembles a lark's spur or claw.
Delphiniums have been cultivated and hybridized for decades. There are over 300 annual, biennial and perennial species, with most delphiniums in today’s gardens being complex perennial hybrids of Delphinium x elatum, commonly known as the bee delphinium.
To add a little more confusion, plant taxonomists have placed several annual species in their own genus, Consolida. These plants have daintier flower spikes with fewer florets and fine, more deeply cut leaves. Larkspur is the common name for all the Consolida annual species. No wonder gardeners get confused by botanical names!
Image Right - Flowers may have a single layer of petals or have a double row of petals like these. Image from Pixabay.
Tall to Small
Some perennial delphiniums grow up to 5-6 feet tall, making them good background plants. Medium-sized plants, growing 2-3 feet tall are a good choice for the middle or front of the perennial border. But there are shorter cultivars available, too. Choose the type that works best for your garden.
One of the most widely available perennial species is belladonna delphinium (D. x belladonna), a cross between D. elatum (bee delphinium) and D. grandiflorum (Chinese delphinium). Plants produce multiple flower stems that grow to 1-4 feet. Plants flower from midsummer to fall, usually with single cup-shaped flowers. Below are a few beautiful Chinese delphiniums are worth consideration.
- ‘Summer Cloud’ has deep blue flowers with a white eye and grows 10-12” in height.
- ‘Summer Nights’ has midnight blue flowers and grows 10-12” in height.
- 'Blue Butterfly’ has rich blue flowers and only 12-18” in height.
Image upper left: Delphinium 'Summer Blues'. Image from Monrovia Nursery, monrovia.com.
Other great D. elatum hybrids include the following, listed by height.
- Connecticut Yankee series. Typically 2-2.5 feet tall with more heavily branched plants. A variety of flower colors.
- Magic Fountain strain. Grows 2.5-3 feet tall with a variety of flowers colors in white, white with a dark center, dark blue, sky blue and pink.>
- Million Dollar series. Grows 2.5-3 feet tall. Sturdy stems with semi-double to double flowers. Very heat tolerant.
- Centurion series. Upright stems with semi-double flowers. About 3 feet tall.
- New Millenium series. Typically 3-4 feet tall and come in a variety of flower colors.
- Mid-century hybrids grow 4-5 feet tall and have stronger stems than other tall delphiniums. Also more resistant to powdery mildew.
- Pacific Giant series. Usually grown from seed, so variation in flower color is common. From 3-6 feet tall.
Delphiniums perform best in fertile, humus rich, well-drained soils in full sun. They are heavy feeders and should be fertilized in early spring and later in the season. Stunted growth and yellow foliage are signs the plants need additional fertilizer. Keep plants well-watered and mulched during typical summer dry periods.
Nebraska’s strong winds are a problem for delphiniums. The flower spikes are hollow and brittle. Tall hybrids should be staked as wind and rain on the heavy, flower-laden spikes will bend or snap the stems. Stakes should be installed early in the growing season to prevent damage to the plant's root system and provide early support.
Most delphinium hybrids bloom from early to mid-summer. They are excellent cut flowers and will last about 6 to 8 days in a vase. Immediately after flowering, cut off the old flower stalk to encourage additional flowering in late summer or early fall. The flower spikes produced during the second flower display won't be as large or as full as the first bloom.
Flower spikes can easily be air-dried. Harvest spikes when about four-fifths of the florets on the spikes are open. Remove the foliage and hang small bunches of spikes upside down in a dark, well-ventilated area. When the flowers feel papery, they should be stood upright to finish drying.
While delphiniums are spectacular plants, but many are short-lived perennials. Most last only 2 or 3 years in the garden.
A word of caution to gardeners with small children. All parts of the delphinium and larkspur are poisonous.
Image right: Delphinium 'Delphina Dark Blue White Eye' has dark purple flowers with a white eye. Image from Proven Winners, provenwinners.com.