Didiscus spp.

blue lace flower

Attracts Pollinators Attracts Butterflies Fragrant (light)Container Friendly

Overview

Didiscus spp. is a name applied to a group of annual and perennial herbs in the carrot family from Australia, now generally treated within the genus Trachymene spp.. The widely grown plant is the blue lace flower, Trachymene caerulea (long sold as Didiscus caeruleus), an upright annual 18-24 inches (45-60 cm) tall with deeply divided, light green, slightly hairy leaves. Through summer the branching stems carry rounded, domed umbels 2-3 inches (5-8 cm) across, packed with many tiny lavender-blue to pale blue flowers, resembling a softer, blue version of the lace-cap umbels of Queen Anne's lace. The flowers are scented and draw bees and other insects, and the long, wiry stems are cut for the vase. The genus grows in full sun on light, free-draining soil and tolerates heat and dry spells once established, though it does poorly with root disturbance and on damp, heavy ground. Plants are frost-tender and are grown as warm-season annuals, sown where they are to flower or potted on carefully. Seed germinates in darkness and warmth. Plants flower a few months after sowing and finish as the season cools.

Native Range

Native to Australia, with the blue lace flower native to Western Australia, growing in sandy soils and open, sunny sites.

Suggested Uses

Grown in sunny borders, cutting gardens, and containers for the domed blue summer flowers, which last well in the vase. Suited to warm-season bedding and pollinator plantings. Plants are not frost-hardy and fail in cold, wet soils.

How to Identify

Recognized by an upright annual with deeply cut, ferny, light green leaves and domed umbels of many tiny lavender-blue flowers. The flower clusters sit on long, slender stalks above the foliage. The form recalls a blue, rounded version of Queen Anne's lace.

Appearance

Size & Dimensions

Height1'6" - 2'

Width/Spread8" - 1'

Colors

Flower Colors

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~10 weeks

Summer Fall

Flowering runs through summer into early autumn, several months after a spring sowing. The blue umbels open over a long period and are followed by small, dry seeds. Removing faded heads prolongs flowering.

Detailed Descriptions

Flower Description

lavender-blue to pale blue

Foliage Description

light green

Growing Conditions

Sun Requirements

SunFull Sun

Requires 6-12 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range6.0 - 7.5(Neutral)

357912

Soil Types

sand loam

Drainagewell drained

Water & Climate

Water Needs

Medium

Care & Maintenance

Care Guide

Plants grow in full sun on light, free-draining, sandy soil of low to moderate fertility. Seed is sown in warmth and darkness where the plants are to grow, or started in pots and moved on with care, as the roots are easily damaged by disturbance. Seedlings are thinned or spaced 8-10 inches (20-25 cm) apart and kept evenly moist until established, after which they tolerate some drought. Hot, dry winds and damp, heavy soils both reduce performance. Tall plants in open sites may need light support. Plants are frost-tender and finish with the first frosts.

Pruning

Spent flower heads are cut off through summer to extend the flowering period and supply stems for cutting. No structural pruning is needed on these annuals. Plants are pulled once they brown and set seed in autumn.