Delphiniums are stately border perennials which come in a wonderful variety of colours. Strong blues and clear whites are colours which are often hard to find in the garden. The delphinium is one of the few plants to give a true blue colour. The delphinium also adds greatly to the height of the garden. If well staked it can tower above the other foliage to give an eye catching display.

Growing Delphinium from Seed.

Delphinium seed is expensive. A packet may only have a few seeds in. But, they are good fun to grow from seed. Make sure you get a good variety from a reputable supplier.

• Sow seed in January / February under glass and gentle heat, and keep well protected from frost and cold.
• Sow in 3 inch pots and grow one plant per pot.
• In April / May start to move outside before planting out.
• Delphinium Seed
• You can acquire or just admire plants as part of a collection

Soil Preparation for Delphinium

Like many plants delphiniums like well drained fertile soil. If possible work in leaf mould / well rotted compost into the soil to improve the humus  / organic content. Top dresser with a general fertiliser. If the soil is clay based then drainage may be a problem, in this case work in sand or grit to the place where they will grow.

Staking Delphiniums. The flower stems of Delphiniums are so dominating they are unfortunately top heavy. Therefore, they need appropriate staking to prevent blowing over.

Pests and Diseases.

If you’ve ever tried growing delphiniums you will have learnt by experience that they are loved not just by gardeners but also slugs. They lush leaves are particularly attractive when they first appear. If you are not vigilant the whole plant can be destroyed over night. For organic methods, try controlling population with nemotodes, applying in autumn is particularly effective. The alternative is the ubiquitous slug pellet. If you rely on sharp material around the plants, you may fail as it often fails to discourage slugs.

Other Tips for Delphiniums

• Try dividing and splitting plants in March and April and replant. You can also try taking stem cuttings from new shoots in April. The shoots should be around 4-5 inch in length and potted into a suitable gritty potting mixture. See: Stem cuttings from Delphiniums
• Keep well watered, especially during flowering season. This makes plant less susceptible to mildew.
• Try deadheading for a second flush, later in the year.

Blue Varieties of Delphiniums

• ‘Min’ – a dark-eyed lavender blue (160 cm)
• ‘Langdon’s Pandora’ – a black-eyed mid-blue (240 cm)
• ‘Fenella’ – a black-eyed gentian blue (165 cm)
• ‘Blue Nile’ – a white-eyed dark blue (180 cm)
• Centurion Sky Blue
• Centurion Gentian Blue

Delphinium Cuttings

Delphinium growing at BBC

Credit Delphiniums by Paul Gulliver, CC BY-NC-SA 2.0