Delphinium Tall spires of delphiniums add colour and drama to summer borders during their short flowering season. As classic cottage garden plants, they also give a strong vertical accent in groups of mixed perennials.

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History Cultivation

Recommended varieties Problem solver

The ancient Greeks thought the flower bud resembled a dolphin, hence the name Delphinium. In Tudor England, the common name 'larkspur' referred to the flower's supposed similarity to a lark's claw.

Modern delphiniums are hybrids. Breeders crossed species such as D. elatum from the Swiss Alps, D. cheilanthum, a dark-blue Siberian species, and the purple, hooded D. brunonianum from the Himalayas. The commonly grown modern Delphinium elatum type has evolved from these crosses, with the large forms we recognise today having been developed in the early 20th century.

Delphiniums perform best in a sunny, open site with fertile, well-manured soil. Remove weak growth in spring, leaving only vigorous shoots. Water generously every ten days in spring and early summer, and feed regularly to boost flowering. The removal of old spikes may prompt further flowering in late summer.

Tall cultivars need support. Four stakes per plant, put in place around the plant in spring, works best. Add new ties as the plant gains height.

All parts of the plant are poisonous if eaten, and foliage may cause skin irritation.

Plants tend to lose their flowering potential after about three years, so take cuttings.

Watch Monty Don's guide to dividing delphiniums:

Elatum group

These towering, upright perennials are the delphinium of traditional herbaceous borders and make a dramatic display when planted in groups of three or more. The dense spikes of semi-double flowers reach 1.5m to 2.5m (5ft to 8ft) in height and come in a range of colours, with the 'eye' often a contrasting colour. Propagate using cuttings only.

• D. 'Black Night Group' - boasts sumptuous purple flowers with black eyes.
• D. 'Finsteraarhorn' is a new, delicate-looking, gentian-blue cultivar.
• D. 'Black Arrow' is an unusual variety with dramatic purple-black flowers.
• D. 'Blue Dawn': pale-blue flowers, flushed pink, with a dark brown eye.
• D. 'Blue Nile': intense deep blue, with a paler eye.
• D. 'Sandpiper': cream-coloured eyes set against white petals.
• D. 'Sungleam': pale-yellow flowers with yellow eyes.
• D. 'Lord Butler': mid-blue flowers.
• D. 'Emily Hawkins': pale blue with a lilac tinge.

Belladonna group

Belladonna delphiniums are shorter and bushier than Elatum types. Flowers are spurred, and packed tightly on short spikes. These varieties are more resistant to powdery mildew than other types. Propagate by division, or take basal cuttings from fresh shoots in spring.

• D. ‘Volkerfrieden: the intensity of the blue flowers makes this variety particularly effective in large groups.
• D. 'Ballkleid': mid-blue flowers, widely spaced.
• D. 'Cliveden Beauty': delicate pale-blue flowers, equally effective in a border or as a cut flower.

Species delphiniums

• D. tatsienense: a shorter delphinium - about 30cm (1ft) - that shines at the front of a border or in a rock garden. The intense cornflower-blue flowers appear in early summer.

Slugs adore delphiniums. The plants are also often prone to mildew in hot summers. Find out how to treat any problem plants with our Pest and Disease Identifier

Where to see them

The National Collection of Delphiniums is held at Rougham Hall Nurseries.

• Mr K G Harbutt
• Rougham Hall Nurseries
• Ipswich Road (A14)
• Rougham
• Bury St Edmunds
• Suffolk, IP30 9LZ
• Tel: 0800 970 7516
• Website: www.roughamhallnurseries.co.uk