Height 30cm-1.2m (1-4ft)
Planting distance 23-30cm (9-12in)
Flowers early to late summer
Sunny or lightly shaded site
One of the most enchanting sights in a summer herbaceous border is a mass of blue, white and pink delphinium spires soaring into the sky above attractive fern-like foliage. Two species — Delphinium ajacis and D. consolida and their varieties – are hardy annuals.
Commonly known as larkspurs, they reach 30cm-1.2m (1-4ft) so should be grown in herbaceous borders where there is plenty of space. Though blue and white are the most common flower colours, shades of pink, lavender and mauve are also available.
Delphinium ajacis, or rocket lark-spur, reaches 30-90cm (1-3ft) high and has sparsely branching stems bearing spires of loosely arranged. The hyacinth-flowered hybrids are the most commonly grown – they make excellent cut flowers as well as decoration for borders. They come in blues, purples, pinks and whites. ‘Tall Rocket Mixed’ reaches 75cm (30in) high and ‘Dwarf Rocket Mixed’ reaches 38cm (15in) high. Delphinium consolida, larkspur, is a taller species reaching 1.2m (4ft) high, with a more branching habit. The flowers are arranged in densely packed spikes and come in blue, red, purple, pink and white. Popular varieties and strains include ‘Sublime Mixed’ (long spires of double flowers on 90cm/3ft high plants).
Sow the seeds in their flowering site in early to. Thin to the necessary planting distances when the seedlings are large enough to handle: 23-30cm (9-12in) for rocket larkspur and its varieties, and 30cm (12in) for larkspur and its varieties.
For large, early-flowering plants, seeds may be sown in early autumn.
Annual delphiniums like fer- tile, well-drained soil in full sun or partial shade. Support tall varieties with twiggy sticks, and cut out faded stems after flowering.
Pests and diseases
Slugs and snails andmay affect leaves, stems and flowers.