PL. —Trichostema lanatumBotanical illustration — drop image
Trichostema lanatum

Woolly Blue Curls

SpringSummer
8a10bHardiness zone
Peak bloom windowZone 6b · frost-offset weeks
Winter
Not in bloom
Spring
Peak bloom
Summer
Peak bloom
Fall
In bloom
Peak bloom
In bloom
Background

Trichostema lanatum is a small evergreen shrub endemic to the coastal chaparral of California and the northern tip of Baja California. It produces dense, woolly spikes of deep blue to violet flowers with long, arching stamens from late spring well into summer, making it one of the most visually distinctive native shrubs available for dry ornamental and habitat gardens.

It demands full sun, lean sandy or rocky soil, and minimal irrigation once established. Poor drainage or clay soil causes rapid decline. A light pruning of one-third of stem length after the main bloom period keeps plants compact and may promote a secondary flush. Summer watering should be kept to a bare minimum; consistent moisture in warm weather is the most common cause of plant loss. Established plants are long-lived under correct conditions and require little maintenance.

Chumash people brewed a leaf infusion used traditionally for colds and fever. The aromatic foliage contains volatile oils with documented antimicrobial activity in ethnobotanical literature. In the landscape, the flowers reliably attract native bees, bumblebees, and hummingbirds across the extended bloom season.

Care guide
SunFull sun
WaterLow
SoilSandy, well-drained, lean
Spacing3–5 ft
Height2–5 ft
Zone8a – 10b
Native RegionCA
Seasonal tasks
winter
watchInspect drainage after sustained rain; standing water at the root zone triggers rapid crown and root rot.
spring
cutRemove dead or crossing branches in late winter before new growth resumes; avoid cutting into old woody stems, which recover poorly.
sowTake softwood cuttings in late spring, treat cut ends with rooting hormone, and root in a gritty, well-drained mix; cuttings are the most reliable propagation method.
summer
cutPrune stems back by one-third after the first main bloom flush to encourage a second wave and prevent legginess.
fall
sowPlant container-grown transplants in fall into fast-draining lean soil; do not amend with compost or fertilizer.
watchCheck for powdery mildew in humid coastal microclimates; thin congested interior stems to improve air circulation.
Common problems

Phytophthora Root Rot

Symptoms

Wilting despite moist soil, yellowing leaves, stunted growth, and dark, decayed roots and crown tissue. Vines may collapse during hot weather.

Treatment

Plant in well-draining soil and avoid waterlogging. Remove and destroy affected vines. Improve drainage with raised beds or amended soil and avoid overwatering.

Powdery mildew

Symptoms

White or grey powdery coating on leaves — usually starting on older growth in humid conditions or when nights cool.

Treatment

Improve air circulation by thinning plants. Apply neem oil or potassium bicarbonate spray at first sign. Avoid overhead watering.

Armillaria Root Rot

Symptoms

Thinning, yellowing canopy with progressive dieback; white, fan-shaped mycelial mats visible beneath bark at or just below the soil line; honey-colored mushroom clusters appearing at the trunk base or on surface roots in autumn.

Treatment

No chemical cure exists. Improve drainage and avoid any injury to roots or trunk. Remove severely infected trees along with as much root material as possible. Do not replant susceptible species in the same spot.