Delphinium (lat. Delphinium) is a genus of herbaceous plants in the family of Ranunculaceae. The common name is larkspur. There are about 450 species of annual and perennial plants. Annual delphiniums that include about 40 species are sometimes referred to an adjacent genus Consolida. Delphiniums grow in China (about 150 species) and throughout Southeast Asia, in the mountains of tropical Africa, in the Northern and Southern Hemispheres.
It is believed that the unopened delphinium flower looks like a dolphin's head, but there is an opinion that the delphinium flowers received its name in honor of the Greek city of Delphi, in the vicinity of which they grew in a great amount. Anyway, all florists will agree that this luxurious flower will decorate any flower garden.
Features of delphinium flower
Growing of delphinium is not an easy task, it requires knowledge and work. Firstly, the planting site must be in full sun in the morning and protected from a strong wind, also water should not stagnate, otherwise delphinium will just rot. After planting mulching with peat or humus is mandatory. On one site delphiniums grow no more than 5-6 years, and Pacific species are less durable and can grow on one site no more than 3-4 years, then the bushes should be divided and planted out. Delphiniums should be staked several times during a season for their hollow stems not to get broken by wind. In addition, the delphinium is susceptible to powdery mildew and some pest species. But if you care for delphinium properly, it will reward you with a vigorous prolonged flowering in June and one more flowering in August or September that will be shorter but no less beautiful.
Species of delphinium
There are annual and perennial delphiniums. The most popular varieties of annual delphiniums are field larkspur and the delphinium ajacis.
Filed delphinium (Delphinium Consolida)
is 6.6 ft high. Flowers of the inflorescences are simple or double, pink, white, lilac or blue. It has been cultivated since 1572. Frosted Sky varieties (blue flowers with white center), pale pink Rose and dark blue Dark Blue look very impressive. Field delphinium blooms in early summer until autumn.
is a hybrid of doubtful larkspur and East delphinium and it has the best of their qualities as a result of breeding. The stem of this species is from 1.3 to 3.3 ft in height, almost sessile leaves are strongly dissected, spicate inflorescences reaching 11.8 inches in length have a variety of flower colors: violet, red, blue, pink, blue and white. The flowers of some varieties are fully double. There are dwarf varieties such as Dwarf Hyacinth, up to 11.8 inches high with double flowers of purple, pink, crimson and white colors. Delphinium ajacis blooms from June till the frosts.
Cultivation of the perennial delphiniums began in the 19th century: on the basis of the first perennials delphinium elatum (Alpine delphinium) and delphinium grandiflorum (Siberian larkspure) the first hybrids were obtained, and then the French flower breeder Victor Lemoine created the double forms of perennials of purple, blue and lavender colors named delphinium ornatum or hybrid delphinium (delphinium hybridum), and then renamed into delphinium cultorum. Today there are up to 800 flower colors of perennial delphiniums! Among them there are tall, medium-height and low-growing varieties with simple, semi-double, double and fully-double flowers ranging in size from 0.8 to 3.5 inches in diameter.
Hybrid perennials are divided into groups according to the place of origin. The most popular are Scottish (hybrids F1), New Zealand delphiniums (New Millennium Delphiniums, or New Zealand Hybrids) and Marfin hybrids, named after the state farm “Marfino”. Each group has its own features and advantages. Marfin hybrids, for example, have excellent frost resistance and are very ornamental, they have large semi-double flowers with a bright contrast spot ( “Blue Lace”, “Morpheus”, “Spring Snow”, “Pink Sunset”). But it is very difficult to grow a Marfin perennial delphinium from seeds since the seeds do not preserve varietal characteristics.
Being recently created, the New Zealand groupis distinguished by its high growth (up to 7.2 ft), large semi-double or double flowers (2.7-3.5 inches in diameter), and some species have wavy petals. These hybrids are frost-resistant, insusceptible to diseases, durable, perfect cut flowers, and that's why they are the most popular today. Cultivation of New Zealand delphiniums is a rewarding and profitable business, if you earn money by selling flowers. Popular varieties are Sunny Skies, Green Twist, Pagan Purples, Blue Lace, Sweethearts.
The creator of the Scottish hybrid perennial delphiniums is Tony Coakley. These hybrids are distinguished by very fully double and double inflorescences, sometimes having up to 58 petals. If the plant reaches 3.6-5 ft in height, the inflorescence can be 2.6 ft in length! Scottish hybrids have a wide flower color palette. They are minimal care plants, long-flowering and perfectly retain their varietal properties during seed reproduction. The most famous varieties are the Morning Sunrise, Blueberry Pie, Moon Light, Sweet Sensation, Crystal Delight and Deepest Pink.
Growing of delphinium from seeds
Sowing of delphinium
Growing of perennial delphinium from seeds is not only a profitable but also fascinating business if compared with the purchase of planting material. Delphinium is propagated by seeds, the rhizome division, by buds and cuttings, but in this section we will tell you how to grow delphinium from seeds. Sowing of delphinium is carried out at the end of February. Remember that when storing seeds in a dry warm place, the germination capacity is lost. Fresh seeds must be sown immediately or kept in the refrigerator until the right time.
Before sowing it is necessary to disinfect the seeds: placing them in a gauze bag, immerse them in a solution of potassium permanganate of dense pink color for twenty minutes. Instead of potassium permanganate, a fungicide can be used and it should be prepared according to the instructions. Then, without removing the seeds from the bag, thoroughly rinse the seeds with cold water and soak in a solution of root hormone for a day. After that dry the seeds so that they do not get sticked to each other.
Prepare the soil for the seeds: take peat, garden soil and humus (compost) in an equal amount, add a half part of the washed sand, sift the mixture. To increase the moisture capacity and looseness of the soil, add perlite at a rate of half a glass to 1 gallon of soil mixture. Now heat the mixture on a water bath for an hour to destroy the seeds of weeds and spores of mushrooms. Fill the seed starter pots with a mixture and lightly compact it.
Planting of delphinium: scatter the seeds over the soil surface, immediately fixing the labels with the name of the variety and the date of sowing. Sprinkle the seeds with the 0.11 inch layer of soil mixture so that the seeds are not washed away when first watered, and slightly compact the topsoil layer. Gently pour or sprinkle the surface with cold boiled water. Cover the container with a transparent lid, and then with black foil or cover material, as the delphinium seeds grow better in the dark, and place the container on the windowsill near the glass. The best temperature for seed germination is 50-59 °F. To increase the germination, in 3-4 days place the container in the refrigerator or on the glassed balcony and do not be afraid if the night temperature drops to 23 °F. In two weeks, place the container with the seeds on the windowsill. After this procedure (stratification) the shoots should appear in a week or two, and try not to miss this moment as you should immediately remove the foil. You should prevent the soil from getting dried out, spray it from time to time and air the container to get rid of the condensate.
Seedlings of delphinium
Healthy sprouts are dark green, strong, their cotyledons are pointed. When the plants have 2-3 leaves, you can prickle the plants in 7-11 fl oz pots, and then grow them at a temperature of no higher than 68°F. Soil must be loose, light. Watering should be very moderate to avoid a “blackleg” disease that will lead to the death of seedlings. Since the beginning of May, gradually accustom the seedlings to fresh air, without removing them from the windowsill during airing. Keep it in the bright sun for a while. Before planting in the soil, feed the delphinium seedlings with combined fertilizers 1-2 times with a 2 week break. The fertilizers should not get on the leaves. Adult seedlings can be planted in the open ground, when the lump of soil in the pot is fully filled with roots – the seedlings are easily removed with the lump without damaging the root system.
Planting of delphinium
The seedlings of delphinium are planted out in the open ground when the threat of night frost passes. As already mentioned, the planting site should be sunny in the morning and without stagnation of moisture. The planting holes are dug at a distance of 2-2.3 ft from each other, the diameter of holes should be 1.3 ft and the depth is 1.6 ft, pour half a bucket of humus (compost), two tablespoons of a combined fertilizer and a glass of ash into each hole, mix it with the soil so that fertilizers do not got on the root of the plant, then make a deepening, put a seedling into it, compact the soil around it and water it. For the first time it is better to cover each seedling with a plastic bottle or a glass jar until the plants take root properly, but once the delphiniums start growing, the cover needs to be removed.
Care for delphinium
When the shoots are 4-6 inches long, they are fed with a solution of cow dung at the rate of 1 bucket of manure per 10 buckets of water for 5 large shrubs. After weeding and loosening of the soil, the flower beds should be mulched with a 1.2 inch layer of humus or peat. When the stems are 7.8-11.8 inches high, the bush should be thinned: keep 3-5 stems on a bush to get large and beautiful inflorescences. Remove the weak shoots of the inner part of the bush, breaking or cutting them off at the base. This will protect the plant from diseases and allow air to circulate. If the cuttings are not hollow and cut with a heel (part of the rootstock), they can be rooted. The cut is treated with a mixture of charcoal and crushed pills of heteroauxin, the cuttings are planted in a mixture of sand and peat and covered with a foil. In 3-6 weeks the cutting starts taking roots, and two weeks later it is planted in the open ground. This is the answer to the question of how to grow delphinium vegetatively by cuttings.
When the plants reach 15.7-19.6 inches in height, trying not to damage the roots, near each bush you should dig in three 6 ft supporting rods to which the stems of the plant are staked with ribbons or strips of cloth, so that when there is a strong wind, they do not cut into stems and do not hurt them. The next staking is done at a height of 3.3-4 ft.
During the growing season, each delphinium drinks up to 13 gallons of water. How to grow delphinium in the heat? You need to pour 2-3 buckets of water for each bush weekly. When the soil dries after watering, you need to loosen it to a depth of 1.2-2 inches. Delphiniums need watering especially during the formation of inflorescences, and if there is a heat during this period, then the inflorescence will get “gaps of the truss”, that is, the areas without flowers. To avoid this delphinium needs heavy watering and top-dressing with potash phosphorus fertilizers at the rate of 0.7 oz of fertilizer per bucket of water, 35 fl oz of solution for each bush.
In the second half of summer, powdery mildew may appear on the plants. It is a fungal disease covering the leaves with a white coating that then becomes brown. If it is not treated timely, the entire aboveground part of the plant will die. When the first signs are noticed, you need to spray delphinium with a solution of fungicide two times. Sometimes on the leaves of the delphinium there are black spots, spreading from the bottom of the plant to the top. This is a black spot that can only be treated at an early stage by twice spraying the leaves with tetracycline solution in the proportion of 1 tablet per 35 fl oz of water. Delphiniums can get affected by ringspot that covers the leaves with yellow spots. This is a viral disease, it can not be cured, and the affected plants will have to be removed. But it is necessary to fight with aphids that can be a carrier of the virus: spray the plants with carbophos or Actellic for preventative measures. The plant can be attacked by the delphinium fly, laying eggs in buds, and slugs. The fly is controlled by insecticide, and slugs are scared off by the smell of bleach that can be placed in jars between the delphinium bushes.
After flowering the inflorescences are cut off, seeds are harvested, but new shoots appear and in autumn delphiniums bloom once more. At the end of summer or early autumn, between the first and second flowering, you can divide three-four-year-old shrubs of delphinium. The bush needs to be dug out, neatly divided or cut with a knife so as not to damage the buds of renewal, the places of cuts are sprinkled with wood ash and the separated parts are planted out. This is another way of vegetative reproduction of delphinium.
Delphinium after flowering
When the leaves wither after flowering, the stems of delphinium are cut at a height of 11.8-15.7 inches from the ground and for safety reasons the top of the tube (the hollow stem) is covered with clay. This should be done so that autumn rains and melt water do not get through the cavity to the root neck and do not lead to the death of the plant from decay of the rhizome. Almost all delphiniums are frost-hardy, both adult plants and seedlings. If winter is cold and snowless, beds with delphiniums should be covered with fir twigs or straw. The plants can be seriously damaged only by frequent and sharp temperature drops, because they lead to an excess of moisture that can make the rhizomes rot. The best way to avoid this is to add half a bucket of sand into the planting hole, so that excess moisture can go deep through it.
You might think that dealing with this plant, especially growing of delphinium from seeds, is too troublesome, but if care for it properly and spend a little time and effort, the results will exceed all your expectations.
References and links
- Read also about topic at Wikipedia
- Features and other plants of the family Ranunculaceae
- List of all species on The Plant List
- More information at World Flora Online