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Trichostema spp.

Bluecurls

Attracts Pollinators Attracts Butterflies Attracts Hummingbirds Deer Resistant Drought Tolerant Fragrant (strong)Container Friendly

Native to North America

SunFull Sun

WaterLow · drought-tolerant

Overview

Trichostema spp. is a genus of about sixteen aromatic plants in the mint family, Lamiaceae, native to North America. It includes both slender annuals and woody evergreen shrubs, ranging from 1-5 feet (0.3-1.5 m) tall, all with paired leaves that release a strong scent when crushed. The flowers give the genus its common name, bluecurls: the petals form a blue to violet tube, and four long stamens arch up and out in a curving sweep well beyond the petals. The woolly bluecurls, T. lanatum, is a Californian shrub with grey, needle-like leaves and dense spikes wrapped in blue-purple wool, while the forked bluecurls, T. dichotomum, is an eastern annual of dry, sandy ground. The vinegar weed, T. lanceolatum, carries a sharp, medicinal smell and grows on disturbed soil in the West. Most species grow on open, sunny, dry sites and bloom from summer into autumn, drawing bees. The shrubby species are short-lived and decline in wet soil or where roots are disturbed, while the annuals complete their cycle in a single season and self-sow.

Native Range

Native to North America, from southern Canada through the United States to Mexico, with separate centres of species in California and in the eastern and central states, on dry, open, often sandy or rocky ground.

Suggested Uses

The woolly bluecurls is grown in dry, sunny borders, gravel gardens, and water-wise plantings for its blue flower spikes and aromatic foliage. The annual species are used in wildflower and pollinator plantings on dry, sandy soil.

How to Identify

Recognised by aromatic, paired leaves and blue to violet two-lipped flowers from which four long, curved stamens arch far beyond the petals. The woolly Californian shrub has needle-like grey leaves and felted blue-purple flower spikes; the eastern annuals are slender with smaller scattered flowers. The long arching stamens and minty scent mark out Trichostema spp..

Appearance

Size & Dimensions

Height1' - 5'

Width/Spread1' - 4'

Colors

Flower Colors

blue

purple

Foliage Colors

green

Bloom Information

Bloom Period

~10 weeks

Summer Fall

Flowering runs from summer into autumn, with the blue flowers opening a few at a time over many weeks. The long stamens present pollen well above the flower, and bees are the main visitors. The annual species flower until frost, then set seed and die.

Detailed Descriptions

Flower Description

blue to violet

Foliage Description

green to grey-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 Range5.5 - 7.5(Neutral)

357912

Soil Types

sand loam rocky

Drainagewell drained

Water & Climate

Water Needs

Low

Drought Tolerance

Drought tolerant when established

Care & Maintenance

Care Guide

Plants grow in full sun in light, sharply drained soil with a pH of about 5.5 to 7.5, and tolerate poor, dry, sandy ground. They need little water once established and are quickly lost in wet or heavy soil, especially the shrubby species over winter. The woolly bluecurls is frost-tender and grown outdoors in mild, dry-summer climates, roughly zones 8 to 10, while the annuals are raised from seed anywhere in a warm season. Seed is sown in autumn or spring, and shrubs can be grown from semi-ripe cuttings. Sharp drainage and air movement reduce the root and stem rots that affect them in humid conditions.

Pruning

The shrubby species are lightly tip-pruned after flowering to keep a compact shape, avoiding cuts into old bare wood, which regrows poorly. Spent annual plants are pulled once seed has set. Removing faded spikes can extend bloom on the shrubs.