Delphinium Flowers

Delphinium, the annual or rocket larkspur (Consolida ajacis, formerly Delphinium consolida / ajacis), is a cool-season hardy annual in the buttercup family grown for its tall, graceful spikes packed with blue, pink, purple or white blooms. Reaching roughly 90-120 cm, it is a classic cottage-garden and florist plant whose airy flowers add height to borders and make a much-loved cut flower for vases.

Planting

Direct-sow where plants will grow, as larkspur dislikes transplanting. In Egypt sow in autumn, ideally November to December, as a winter annual. Set seed about 0.6-1 cm deep and cover it, since the seed needs darkness to sprout. It germinates in about 14-21 days when the soil stays cool, near 13 C; warmer soil gives poor results. Thin seedlings while small to about 10-15 cm apart for dense cutting stems, or 20-30 cm for garden display. Choose a full-sun spot with well-drained, fertile loam at a neutral to slightly alkaline pH (about 6.6-7.3).

Fertilizing

Larkspur needs little feeding, and too much nitrogen produces leaves instead of flowers. In poor soil, mix compost into the top few centimetres at sowing, or apply a balanced, low-nitrogen granular feed such as 5-10-10 once when seedlings are about 8-15 cm tall. Stop feeding once buds appear.

Care

Keep the root zone evenly moist during growth, letting the top 2.5 cm of soil dry slightly between waterings, and water at the base to limit disease. Tall stems usually need support. Watch for aphids, spider mites, slugs, snails and caterpillars, plus powdery mildew, leaf spot, botrytis and root rot; good airflow and a strong water spray help. Cut spikes when up to a third of the florets open for a 5-7 day vase life. All parts are poisonous, so keep away from children and animals.