No other blue quite measures up to the almost iridescent hues of delphiniums commanding the highest post in the garden. Though short-lived, these wonderful old-fashioned flowering plants are well worth cultivating for their magnificent hues--not only blue, but deep purple, pale lavender, palest pink, and snow white.
Visions of Grandmother's garden filled with tall, nodding stalks of brilliant blue, pink, and white Delphiniums adorns many a children's book or notecard, and for good reason. Delphiniums are one of the most beautiful of summer's flowers. However, they have two major drawbacks: they do not live very long - usually only 2 to 3 years - and the plants are highly poisonous. But for their short lives, they share a special place in the garden.
In the buttercup family Ranunculaceae, the genus Delphinium contains almost 300 flowering species. The plants are native to the Northern Hemisphere and some high mountainous regions of tropical Africa. The name Delphinium derives from the Latin word for dolphin, thought to be so named because of the similarity of the opening flower to the sea mammal. Commonly known as Larkspur, Delphiniums are also called Lark's Heel (from Shakespeare), Lark's Claw, and Knight's Spur.
Sky blue and pink-lavender flowers of the Magic Fountains hybrid
Delphiniums are easiest to grow in full sun and moist soil of a neutral to slightly alkaline pH. They require regular fertilization in order to thrive; manure or all purpose fertilizer should be applied around each plant in the spring and again after the first flowering. The tallest varieties require staking, as they will topple and break in wind or from the weight of their own flower stalks. Delphinium varieties range from dwarf 15-inch plants to towering 6-foot beauties.
Flowers are single or double and, though blue is the most common color, newer varieties provide reds, pinks, violets and yellows. Many flowers bloom up the long spikes from early to midsummer. To encourage additional flowering through the season, remove the spent flower stalk. The leaves of Delphinium are palmately lobed into 3 to 7 parts; in some of the newer varieties of Larkspur, such as Delphinium grandiflorum, the leaves are delicate and lacy and the stems are much stronger.
Delphiniums are susceptible to mildew, Botrytis blight, fungal leaf spots, mildew, and crown rot. Insect pests that seem to prefer Delphiniums are aphids, leaf miners, and mites; in wet conditions, the ever-present slug will feast on Delphiniums. A condition called "blacks" is common and results in stunted, deformed plants; the buds turn black and wilt. This damage is not fungal, but is caused by cyclamen mites. To avoid most of these diseases and pests, practice good sanitation around plants and keep area well drained and clear of debris.
Delphiniums can be grown from seed or by basal cuttings. Seed should be started indoors early in the year, and those plants will flower the first year. If seeds are sown in the target location, those plants will not flower until the following year. Seeds germinate in 2 to 4 weeks at 65˚-75˚F. Take cuttings from the new growth in early spring; rooting will occur in 3 to 4 weeks.
As mentioned at the beginning of this article, all parts of the Delphinium are very poisonous; the offending substance is the alkaloid delphinine, which
Delphinium grandiflorum variety with delicate, lacy leaves
causes vomiting when eaten and, in larger quantities, ultimate death. Larkspur is a serious problem for cattle ranchers in the western United States; if eaten, the animals die within a few hours from cardiotoxic and neuromuscular blocking effects.
On the other side of the coin, Larkspur has been used in the past as an herbal medicine, particularly thought to act as an antidote to scorpion stings. Other uses cited were anti-parasitics (especially lice), as a cure for asthma and dropsy, and as a preventative for eye disease. Taking the plant's powers a step further, Larkspur was one of the herbs for the feast of St. John and was thought to ward off lightning! In Transylvania, the seeds' black color was thought to keep witches from the stables.
Today's Delphiniums are mostly hybrids developed from the early 1800's from the species Delphinium elatum, Delphinium grandiflorum, Delphinium exaltatum, and Delphinium formosum. The most commonly available Delphiniums are listed below, according to mature height.
Very Tall: 6 feet
'Astolat'--lavender pink with dark center
'Black Knight'--deep midnight blue
'Blue Bird'--medium blue with white center
'Blackmore & Langdon Hybrids'--white, light blue, deep blue, purple
'Magic Fountains Hybrids'--dark blue, lavender, white, sky blue
'Connecticut Yankee'--light blue, lavender, white
'Blue Springs'--sky blue, blue, lavender
D. grandiflorum 'Blue Mirror'--deep blue
Dwarf: 15 inches
D. nudicaule 'Laurin'--orange-red
Photos by Toni Leland
About Toni Leland
Toni Leland has been writing for over 20 years. As a spokesman for the Ohio State University Master Gardener program, she has written a biweekly newspaper column and is the editor of the Muskingum County MG newsletter, Connections; she currently writes for GRIT, Over the Back Fence, and Country Living magazines. She has been a gardener all her life, working soil all over the world. In her day job, she scripts and produces educational DVDs about caring for Miniature Horses, writes and edits books about them, and has published five novels.