Didiscus Blue Lace

Trachymene coerulea (formerly Didiscus caeruleus) Blue Lace Flower 'Blue Lace'

Elegant umbels of soft, powder-blue flowers held on tall slender stems above lacy ferny foliage — Didiscus 'Blue Lace' is the florist's secret weapon, producing one of the truest blue umbel forms available from seed and a quietly sweet evening fragrance that floats through the cutting garden on still summer afternoons.

A genuinely uncommon cut flower in British gardens, and a small treasure once you've grown it. Each lacy umbel is composed of dozens of tiny powder-blue to pale lavender-blue florets arranged in flat-topped clusters — the same architectural form as Ammi majus or wild carrot, but in a soft, gentle blue that few annuals can match. Tall stems (45–60cm) with finely divided ferny foliage. The plant is native to Western Australia and prefers warm, sunny, sheltered growing conditions in the UK. Half-hardy annual flowering July through September. Faintly but distinctly fragrant — a subtle sweet scent most noticeable in evening air. RHS Plants for Pollinators recognised, with the open umbels accessible to a wide range of bees and beneficial insects.

A note on growing

Sow indoors from March to April at 18–20°C. Cover seeds lightly with compost (about 3mm — they prefer some darkness for germination). Germination takes 14–21 days, sometimes longer. Pot on carefully — Didiscus dislikes root disturbance. Use individual modules or biodegradable pots that can be planted out intact. Plant out only after all risk of frost (late May/June) in a warm, sheltered position in full sun and well-drained soil. Didiscus is genuinely frost-tender and does not tolerate cold wet British conditions in early spring. Drought-tolerant once established. May benefit from light twiggy support if grown in exposed positions.

Where it shines

In the cutting garden as a properly elegant blue umbel cut flower — there are few annuals that provide soft powder-blue colour with such architectural quality. The faint evening fragrance is a quiet bonus. In modern romantic bouquets, where 'Blue Lace' adds the touch of soft blue that's notoriously hard to find in cut flowers. In sheltered cottage borders that get full sun — Didiscus needs warmth and shelter to perform well in British gardens. As a conversation-piece plant for gardeners who appreciate the unusual.

Plant alongside

For a soft sophisticated cutting scheme, combine 'Blue Lace' with Ammi majus (textural sibling — same family of umbel flowers but in white), Cosmos 'Daydream' (white-and-blush ombré matching the soft palette), and Cornflower 'Snowman' for the cool romantic palette. The powder-blue umbels also work beautifully against the deeper indigo of Clary Sage 'Oxford Blue' for a layered blue scheme.