Delphinium

Delphiniums are a hardy clump-forming perennial that can grow to over 2 m (6’6”) tall (depending upon variety) and spread to 900mm (36") wide.

They produce numerous spikes of flowers in various colours throughout summer.

If you require quality flowers rather than quantity, thin out established plants when the basal growth is around 75mm (3") high, reduce the growths to the strongest half dozen.

As with most tall herbaceous plants, they will benefit from some kind of support.

Staking in March/April with three or four canes and soft string (not wire) supporting the whole plant is best.

Do not tie individual spikes to canes, as this rigid form of support is more likely to damage stems.

When new plant growth emerges in early spring, watch out for slug damage, and treat accordingly.

Water well during the growing season, and apply a balanced liquid fertiliser every 2 or 3 weeks.

Plants affected with the bacterial disease Delphinium black spot, should be removed immediately, as there are no alternative chemical controls available to amateur gardeners.

Powdery mildew can be treated with fungicide!

Ailsa

Ann Kenrick

Darling Sue

Elizabeth Cook

Faust

Gertrude Sahin


Jenny Agutter

Sarita

Spindrift

Susan Edmunds

Thamesmead

Unamed seedling


Cultivation

Week 8: Sow seed of grandiflora types in pots or tray of seed compost and germinate at a temperature of 16°-18°C (60°-65°F)

Do not use bottom heat.

Germination can take up to two weeks.

Week 10: Prick out seedlings if large enough to handle, into 70mm (3") pots of potting compost.

Harden off in a cold frame until planting out time.

Week 14: Every three years or so,divide plants if conditions allow and plant out immediately.

Take basal cuttings at the same time if ground conditions are suitable.

To do this, scrape away soil from around the crown of the plants and cut off 75-100mm (3”-4”) solid stemmed basal shoots,(hollow shoots are not suitable) insert these around the edge of a pot filled with a 50-50 mix of compost and sharp sand.

Although artificial heat is desirable, cuttings placed in a well-insulated cold frame or greenhouse should succeed.

Week 27: As the flowers fade, cut back the flowering stems just below the last flower head, this may encourage a second flush of flowers later in the season.

Delphinium seed are short lived, and are best sown when fresh and ripe, therefore collect seed as soon as possible after flowering and sow immediately.

In the event this is not practical store the seed in a domestic refrigerator, at a temperature of 2°C (35°F) until sowing time.

Similarly, sow commercial seed in pots or tray of seed compost and germinate at a temperature of 16°-18°C (60°-65°F)

Alternatively, sow in a nursery bed.

Germination should take about ten days.

Week 30: Prick out seedlings if large enough to handle, into 70mm (3") pots of potting compost.

Harden off in a cold frame until planting out time.

If you receive your plants by mail order pot the plugs up into individual 7.5cm (3in) pots of multi-purpose compost as soon as the arrive.

After potting, grow the plants on in a cold frame or sheltered part of the garden for 4-6 weeks until planting out time.

Week 35: Plant out perennial species 600mm (24") apart in deep humus rich soil.

Select a sunny position that is sheltered from high winds.

Week 43: Cut down plants to ground level after leaves have died back.





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