Delphinium

Delphinium

A robust family of annuals, biennials and hardy perennials. The tall stately forms are favourite cottage garden plant in the UK. Adored by bees and other pollinating insects.

Family: Ranunculaceae (buttercup family)
Botanical Name: Delphinium
Common Names: Larkspur

Foliage: Deciduous, palmately lobed, basal leaves.

Flowers: Spectacular disc-shaped flowers, clothing tall spikes or erect racemes. Available in shades of white, pink, red, blue and purple (depending on variety).

Flowering Period: June, July, August.

Soil: Moist but well-drained, fertile soil (chalk, sand or loam). Any pH.

Conditions: Best in full sun. Plant in an east, west or south facing aspect, in a very sheltered position.

Habit: Columnar/Upright.

Type: Herbaceous perennial.

Origin: mainly native to the Northern hemisphere.

Hardiness: Most varieties are hardy in the UK.

Toxicity: All parts are an irritant and may cause severe discomfort if ingested.

Planting and Growing Delphiniums

Plant out from autumn to early spring, in a deep, rich loam

Thrives best in a warm sunny border. Choose a sheltered position for tall varieties, which are easily damaged by wind during the flowering season. Stake and tie-in tall varieties as they grow.

Delphiniums are ideal for cottage gardens. They are also good in open flower beds or at the back of the border. Plant a large group of them together in the border for impact, or mix them amongst your other tall-growing cottage garden favourites, such as foxgloves, hollyhocks and lupins.

All forms are loved by flower arrangers. The blooms are highly attractive to bees and other pollinating insects.

Taking Care of Delphiniums

Pruning Delphinium

Dead head after flowering. Cut down to strong leaf node to produce a second flush.

Cut all growth down to ground level in autumn.

Pests and Diseases

Susceptible to attack by slugs, snails, leaf miners and caterpillars.

Can be affected by powdery mildew, delphinium black blotch, wet rot and a virus (especially in poorly cultivated soils).

Propagating Delphiniums

Sow the seed of annuals and perennials where they are to flower, in late spring. Alternatively sow in a prepared seedbed and transplant to final flowering site in autumn.

Sow seed under cover in early spring. Prick out, pot on and plant out at the end of May after hardening off. Alternatively, sow fresh ripe seed as soon as ready.

To increase cultivars and hybrids, take 4in (10cm) basal cuttings of new spring growth near the base. Root in 50/50 mixture of potting compost and horticultural sand, in a cold frame. Grow on and plant out to flowering positions in autumn.

Popular Varieties of Delphinium

There are many different cultivars of Delphinium available from tall to medium and dwarf height, in a wide range of colours. Delphinium elatum is the parent of most modern garden varieties. Average height 5ft (1.5m).

Delphinium 'Astolat' produces rich spikes of deep pink flowers in June and July. A stunning delphinium that looks gorgeous planted in bold clumps for a dramatic statement. Available from Gardening Express.

Delphinium 'Black Knight' produces upright spires of indigo-blue flowers with black eyes in June and July. Height over 5ft (1.7m), spread 30in (75cm). Available from Van Meuwen, Gardening Express, Thompson & Morgan.

Delphinium 'Belladonna Improved' produces blue, white and pink flower spikes, up to 3 ft (90cm).

Delphinium 'Blue Bird' (Pacific Hybrid) produces tall spires bearing bright blue blooms with contrasting white centres. Height to 5ft (1.5m). Available from Thompson & Morgan.

Delphinium 'Dwarf Blue Heaven' is a low growing form with sky-blue, single flowers. Does not require staking)

Delphinium 'Flamenco' is a highly unusual double-flowered variety that sports deep pink-purple blooms. Height to 3ft (90cm). Available from Van Meuwen.

Delphinium 'Galahad' produces tall spires of creamy white flowers. The florets are closely placed on tall stems opening over a period several weeks. Height to 5ft (1.5m). Available from Gardening Express.

Delphinium grandiflorum 'Summer Nights' is a dwarf form covered in a blanket of dainty midnight-blue flowers over a long summer period. Available from Thompson & Morgan.

Delphinium 'King Arthur' produces strong, upright stems topped with a densely-packed spire of vivid deep blue semi-double flowers with white eyes. Available from Gardening Express, Thompson & Morgan.

Delphinium 'Pacific Hybrids' a cottage garden favourite, sometimes referred to as 'Pacific Giants'. Developed in the 1950s and 60s, they are available in a wide range of colours from blue, mauve, chocolate and white. Semi-double or single flowers. Available from Thompson & Morgan.

Delphinium 'Pink Blushes' produces tall spires of beautiful blooms in shades of pink through to magenta. Height to 5ft (1.5m), spread 30in (75cm). Available from Van Meuwen, Thompson & Morgan.

Delphinium 'Princess Caroline' is a strong and robust hybrid Delphinium with striking sturdy flower spikes in a unique salmon colour. Available from Gardening Direct.

Delphinium 'Summer Skies' produces strong stems of intense electric blue florets, reminiscent of a clear blue summer sky. Height to 5ft (1.5m), spread 30in (75cm). Available from Gardening Express, Thompson & Morgan.