Delphinium- Delphinium, Larkspur

Hardy perennial delphiniums are the pride of any summer garden, even though their cultivation is not very simple. There are also attractive annuals.

Situation:

Perennial delphiniums make perfect border plants; the predominantly blue, violet, purple and white shades harmonising with all sorts of other colours. The Pacific Giants are the easiest to grow, but the German hybrids are the most beautiful . The plants must be carefully staked and frequently transplanted, otherwise the clumps rapidly deteriorate. Annual species belong in the annual border and especially where flowers are grown for cutting.

Soil:

Hardy perennials, in particular, require liberally manured, porous soil.

Propagation:

Annuals are sown out of doors. The perennial Pacific Giants are sown from late winter onwards in the greenhouse. Other forms are divided or grown from cuttings in spring.

Delphinium ajacis and Delphinium orientate: There is little difference between these two annual species. Height 40-100 cm; flowering season in summer, the flowers being mainly pink, blue and white; feathery foliage, branched flower spikes. Catalogues distinguish between Imperial larkspurs with strongly branching, double flowers; ‘Hya-cinthiflorum’ or hyacinth-flftwered larkspurs, less dense; viola-flowered larkspurs and dwarf larkspurs, double-flowered, not exceeding 40 cm.

Delphinium hybrids: This group includes all commercially grown types. Height to 2 m; flowering season early to mid summer. After being cut back in early autumn they will flower for a second time. There are three groups:

Belladonna types, not exceeding 1 m, which has the ad-vantage that the plants will not collapse so easily. ‘Capri’ is pale blue; ‘Lamartine’, deep blue; ‘Volkerfrieden’, bright gentian blue.

Elatum types, height 125-200 cm; large flower spikes, magnificent colours. ‘Berghimmel’, pale blue with a white centre; ‘Finsteraarhorn’, deep gentian blue with a darker centre etc.

Pacific Giants, height 150-200 cm, extremely heavy flower spikes. Strains raised from seed will grow practically true to type. ‘Black Knight’, deep violet blue; ‘Blue Bird’, gentian blue; ‘Galahad’, white; and ‘King Arthur’, deep violet with a white centre. be frost at night, the plants can be covered with an inverted flowerpot or a bucket. The plants are lifted in the autumn, before the first night frost occurs, and the stems are severed close to the tubers. The tubers are left to dry for a week and are then kept in dry peat fibre at a minimum temperature of 5°C and a maximum of 10°C. They must be checked from time to time; if they are kept too damp rotting may occur.

The innumerable hybrids are grouped as follows: Cactus Petals rolled along their entire length. Semi-cactus Petals rolled for part of their length only. Decorative The petals are not rolled. Sometimes they are split at the tip .

Peony-flowered Deca-split with an open centre. Pompon Spherical flowers.

Anemone-flowered The flowers resemble anemones. Collarette Single, with a ring of short, differently coloured florets in the centre. Mignon Single, low-growing . Dwarf bedding Small-flowered, low-growing .

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