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Ceanothus oliganthus

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About Hairy Ceanothus (Ceanothus oliganthus) Ceanothus oliganthus is a species of shrub in the buckthorn family Rhamnaceae known by the common name hairy ceanothus. It is endemic to California, where it can be found in most of the coastal mountain ranges in dry habitat such as chaparral. This is a large, erect shrub approaching 3 meters in maximum height. The evergreen leaves are alternately arranged and may be up to 4 centimeters long. They are dark green on top, paler and hairy on the underside, and are edged with hairy teeth. The flower cluster is a cluster or series of clusters of blue or purple flowers. The fruit is a capsule which may be hairy or not, depending on variety. There are three recognized varieties with different ranges. The variety of this species known as jimbrush (var. sorediatus) is sometimes treated as a separate species.

Plant Ceanothus oliganthus on rocky slopes, particular north facing ones in the southern, drier parts of its range. This plant is fairly sensitive to summer water. Best to avoid all direct summer water after it's first year, though it will be happiest if it can stretch its roots out to a damper or irrigated area 10 feet away or so. This plant likes full sun but tolerates part shade.
Plant Description
Plant Type

Max. Height
10 ft (3 m)

Max. Width
12 ft (3.7 m)


Fragrant - Pleasant

Growth Rate


Flower Color
Blue, Purple

Flowering Season
Spring, Winter

Native Status

Natural Setting
Site Type
Rocky, dry slopes below 4,500 ft. most often along the coastal side of the mountains, frequently on north facing aspect, from Humboldt County to San Diego


Elevation ?
3' - 6541'

Annual Precip. ?
5.1" - 154.9"

Summer Precip. ?
0.15" - 2.96"

Coldest Month ?
38.3° F - 55.3° F

Hottest Month ?
60.0° F - 82.9° F

Humidity ?
0.05 vpd - 33.83 vpd

Soil Description
Tolerates both heavy and sandy soils

Soil PH
6.0 - 8.0

Fast, Medium

Cold Tolerance(° F)
Tolerates cold to 15° F

Wildlife Attracted
Various insects and birds. It is host plant to the following butterflies: Spring Azure, Echo Blue, Pacuvius Duskywing, California Tortoiseshell, Pale Swallowtail, and Hedgerow Hairstreak.

Landscaping Information
Ease of Care
Moderately Easy

Water Requirement ?
Very Low
Extremely Low
Very Low
Moderate - High

Seldom Used

Max. Summer Water ?
No Summer Water, 1x/month
No Summer Water
Keep moist

Organic with Rocks

Propagation ?
For propagating by seed: Hot water treatment.

Common uses
Bank Stabilization, Hedges, Deer Resistant, Bird Gardens, Butterfly Gardens, Bee Gardens

Nursery Availability
Commonly Available

Sources include: Wikipedia. All text shown in the "About" section of these pages is available under the Creative Commons Attribution-ShareAlike License. Plant observation data provided by the participants of the California Consortia of Herbaria, Sunset information provided by Jepson Flora Project. Propogation from seed information provided by the Santa Barbara Botanical Garden from "Seed Propagation of Native California Plants" by Dara E. Emery. Sources of plant photos include CalPhotos, Wikimedia Commons, and independent plant photographers who have agreed to share their images with Calscape. Other general sources of information include Calflora, CNPS Manual of Vegetation Online, Jepson Flora Project, Las Pilitas, Theodore Payne, Tree of Life, The Xerces Society, and information provided by CNPS volunteer editors, with special thanks to Don Rideout. Climate data used in creation of plant range maps is from PRISM Climate Group, Oregon State University, using 30 year (1981-2010) annual "normals" at an 800 meter spatial resolution.

Links:   Jepson eFlora Taxon Page  CalPhotos  Wikipedia  Calflora

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