Ceanothus thyrsiflorus Eschsch.
Blueblossom, Bluebrush, Blue Blossom
Rhamnaceae (Buckthorn Family)
Synonym(s): Ceanothus thyrsiflorus var. repens
USDA Symbol: CETH
A large, sometimes tree-like, shrub from 3-20 ft. tall with small, lustrous green, oval leaves. Flower plumes are up to 8 in. long and are made up of light- to deep-blue blossoms dotted with yellow stamens. Large evergreen shrub or small tree with short trunk, many spreading branches, and showy blooms resembling lilacs.
This is the hardiest and largest ceanothus. Each spring the highways of the West Coast display masses of Blue Blossom flowers. Plants can be grown in screens, in hedges, and against walls. Elk and deer browse the foliage. The shrubs form dense thickets after fires and logging. The scientific name, meaning "thyrse-flower," refers to the compact, branched flower cluster; thyrsus is the name of the staff, adorned with leaves and berries, that belonged to Bacchus, the Greek god of wine.
From the Image Gallery
Plant CharacteristicsDuration: Perennial
Leaf Retention: Evergreen
Leaf Complexity: Simple
Fruit Type: Capsule
Size Notes: Up to about 20 feet tall.
Bloom InformationBloom Color: White , Blue
Bloom Time: Mar , Apr , May , Jun
Bloom Notes: Pale to deep blue, rarely white.
DistributionUSA: CA , OR
Native Distribution: Outer CA Coast Ranges, n. to OR
Native Habitat: Coastal wooded slopes & canyons below 2000 ft.
Growing ConditionsLight Requirement: Part Shade
Soil Description: Fairly dry, well-drained soil.
Conditions Comments: Fast growing. Does not tolerate temperatures below 15 degrees.
Value to Beneficial InsectsSpecial Value to Native Bees
Supports Conservation Biological Control
This information was provided by the Pollinator Program at The Xerces Society for Invertebrate Conservation.
PropagationDescription: Most Ceanothus spp. come well from seed. Cuttings of this species may also be successful.
Seed Collection: Because dry capsules disperse their seed abruptly with a sudden ejection, it may be necessary to tie cloth bags around the clusters of capsules to catch the seeds.
Commercially Avail: yes
Find Seed or Plants
View propagation protocol from Native Plants Network.
From the National Organizations DirectoryAccording to the species list provided by Affiliate Organizations, this plant is on display at the following locations:
Santa Barbara Botanic Garden - Santa Barbara, CA
BibliographyBibref 841 - Native Alternatives to Invasive Plants (2006) Burrell, C. C.
Search More Titles in Bibliography
Web ReferenceWebref 30 - Calflora (2018) Calflora
Webref 3 - Flora of North America (2014) Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA.
Webref 23 - Southwest Environmental Information Network (2009) SEINet - Arizona Chapter
Additional resourcesUSDA: Find Ceanothus thyrsiflorus in USDA Plants
FNA: Find Ceanothus thyrsiflorus in the Flora of North America (if available)
Google: Search Google for Ceanothus thyrsiflorus
MetadataRecord Modified: 2023-05-08
Research By: TWC Staff