Larkspur (Delphinium Flower)
Larkspur (Delphinium) are undoubtedly among the most famous garden shrubs. The blue-flowering and up to man-high plants belong to the Ranunculaceae family and it is estimated that there are about 300 species worldwide – mainly perennials, but also some annual and biennial plants. About half of them are native to China, a quarter to North America and the rest to Europe and the African highlands. The wild species Delphinium elatum occurs in the Alps – one of the most important ancestors of many garden forms, the so-called Elatum hybrids. Also at home in Germany is the one-year-old Acker-Rittersporn (Consolida regalis). It used to be called Delphinium consolida, but is now a genus in its own right. It grows on field margins on calcareous, loamy soils in full sunlight and is classified as endangered on the Red List of Endangered Species.
The Greek name “Delphinium” derives from the shape of the flower buds, which are said to resemble a dolphin. The German name “Rittersporn” also comes from the appearance of the flower and the clear, backward spur at the back of the flowers. Since the poet Novalis in his “Heinrich von Ofterdingen” published in 1802 described the “blue flower” so sensitively, it is regarded as a symbol of romanticism. It stands for unfulfilled longings, the desire for intimate connection with nature and finally for the search for one’s own personal happiness. Then as now, blue flowers exert an almost magical attraction on us.
Larkspur: The most important in brief
Larkspur likes a sunny spot in the garden.
The soil should be loamy-humic and rich in nutrients.
To stimulate a second flower, the shoots are cut back to a hand’s width above the ground after the main flowering in early summer.
A division is recommended in late summer or spring.
Larkspurs are susceptible to powdery mildew; they must be protected from snails, especially when budding.
Appearance and growth
Larkspurs grow upright and can grow up to 120 or even 180 centimetres high, depending on the group they belong to (e.g. Belladonna or Elatum group). Typical are their hand-shaped and fresh green, deeply incised leaves. The high, often branched panicles appear from June to September on strong, hollow stems and, depending on the variety, have light to dark blue, white or violet flowers. In some varieties the colour also changes between blue and violet depending on the incidence of light. Newer varieties even bloom in atypical pink and yellow tones. The flowers appear from the end of June approximately at the same time as those of many rose varieties. On the back of the individual flowers, often decorated with a yellowish, white or black centre, there is a long, slightly curved appendix. This is the eponymous spur, which reminds of the spurs of the armour of the knight’s armour.
Location and soil
Larkspur likes it sunny in the face and shady on the feet. A full sunny garden bed with low underplanting is therefore ideal for Delphinium. Larkspur also love a cool, humid climate. The soil should be sandy-loamy, rich in humus and nutrients, the substrate slightly moist. It is all the more astonishing that Karl Foerster, one of the most important larkspur breeders, has managed to cultivate the demanding perennials in his Potsdam nursery in Brandenburg’s sandy soil. He succeeded in doing this because, according to his own statements, he had plenty of composted cattle manure worked into the soil in his nursery.
Before planting a Larkspur, it is advisable to work some compost into the soil. Since Larkspurs are flat-rooted, you should not insert the root ball too deeply. Planting takes place at a distance of about 60 centimetres. High varieties should be supported with a planting rod in windy locations, otherwise the flower shoots will bend very easily.
When budding in spring, ensure a good nutrient supply with compost and horn meal. In summer, larkspur must be poured regularly. During flowering, it is advisable to apply liquid fertilizer every three weeks for the heavy eater, if the stalks are cut off a hand’s width above the ground immediately after the flowers have withered. That is, they form new, albeit somewhat less luxuriant flower candles up to the late summer. In order to support this feat of strength, you should supply the plants with some fast-acting mineral fertilizer immediately after pruning and ensure even soil moisture in the subsequent period. To prevent water from entering the cut, you can bend the flower stems at the top after cutting.
Especially the Belladonna hybrids are not very long-lived and have to be dug up and divided when their vitality decreases. The Elatum hybrids are somewhat more long-lived, but they too often need a rejuvenating cure on poorer soils after only six years. If possible, do not return the plants to the same place, otherwise there is a risk of stunted growth due to soil fatigue.
Especially for Belladonna hybrids a winter protection is useful in rough locations. If you prune the plants back to a hand’s width above the ground again in autumn, you can use the cuttings as frost protection.
Use of the
With their early to midsummer bloom, Larkspurs are ideal companions for roses – especially as they predominantly bloom in shades that are not found in roses. The impressive flower candles also make an impression in the classic farmer’s garden and in the magnificent herbaceous bed. So that they do not appear too massive, the perennials are set individually, in pairs or at most in groups of three. Tip: To dry the entire inflorescence, you should cut off the branches before opening the flowers and hang them up dry in a dark place.
Important species and varieties
The three main breeds are the more branched Belladonna hybrids, the up to two meter high Elatum hybrids and the popular medium high Pacific hybrids. Belladonna hybrids have a slightly looser flower structure. They are about one meter high and have a service life of three to four years. Elatum hybrids are breeding forms of the High Knight’s Spur (Delphinium elatum) and therefore the largest species. Nevertheless, they are stable and have lush, firm inflorescences with individual flowers up to five centimetres in diameter. Elatum hybrids grow unbranched and are therefore very suitable as cut flowers. In the ornamental garden, the Pacific hybrids have established themselves above all because they show particularly beautiful, large flowers (up to 7.5 centimetres in diameter). They are bred on average one and a half meters high and usually as two-year-olds. The low Pacific varieties are also suitable for planting in tubs. Belladonna hybrids include the Piccolo variety, which blooms in bright gentian blue. Moerheimii’ in pure white contrasts with the dark blue, very compact growing ‘Atlantis’. Ballkleid’ looks very elegant with its light blue, ‘Völkerfrieden’ is a tried and tested variety in gentian blue.
Among the Elatum hybrids, the mildew-resistant ‘feast for the eyes’ captivates with a two-tone blossom in light blue with old rose and a light eye. The stable ‘lance carrier’ blooms gentian blue with a white eye on long flower panicles, ‘arctic fox’ stands compactly in pure white. Overture’ shows a royal game of medium blue and pink with a black eye. Among the trendsetters among the Elatum hybrids are the New Millennium varieties. They captivate by long flower-candles with densely standing, well-shaped single blooms on powerful stems and are frost-hardy. Good varieties are ‘Dusky Maidens’ (dark pink with brown eye), ‘Misty Mauves’ (violet) and ‘Pagan Purples’ (blue lilac). Pacific hybrids have ‘Blue Bird’ medium blue with white eye and ‘Astolat’ in Lilarosa with dark eye. The established variety ‘Black Knight’ has dark purple flowers with a black eye and ‘Galahad’ flowers in pure white.
Larkspur are usually reproduced by division in late summer after flowering or in spring. Even laymen can do this without any problems. The young plants for the nurseries now come almost exclusively from meristem propagation.
Diseases and pests
In hot, dry locations with little air movement, knight spurs are unfortunately very susceptible to disease. Powdery mildew in particular is a problem for perennials. They thrive much more easily in cool, humid coastal climates and at altitudes of around 500 metres and above. In order to prevent mildew, you should pay attention to regular watering. In addition, it can be sprayed with horsetail broth. In case of severe illness, you should remove all infested plant parts and dispose of them with your household waste. Also with snails, all types and sorts of the knight’s spur are very high on the menu. Protect the herbaceous perennials from access by the voracious pests, especially when sprouting. A slug collar, evening collection and slug pellets are helpful. If the leaves turn black, the larkspur has bacteriosis and must be completely removed.