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Ceanothus oliganthus var. oliganthus

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About Hairy Ceanothus (Ceanothus oliganthus var. oliganthus) Hairy Ceanothus (Ceanothus oliganthus var. oliganthus) is a native shrub in the Rhamnaceae (Buckthorn) family. It is one of three recognized varieties of the species. It grows primarily in the coastal hills and mountains of southern and central California, from Santa Barbara County to San Diego County and into Baja. It tends to grow in dry slopes, at elevations from 0-4300 feet. This is a large, erect shrub approaching 3 meters in 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 series of clusters of blue or purple flowers. The fruit is a capsule which is generally smooth.

Plant Ceanothus oliganthus var. oliganthus on rocky slopes, particularly 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. For further information about the species, please refer to Ceanothus oliganthus.
Plant Description
Plant Type

Max. Height
10 ft (3 m)

Max. Width
12 ft (3.7 m)

Fragrant - Pleasant

Summer Semi-Deciduous, Evergreen

Flower Color
Blue, Purple

Flowering Season
Spring, Winter

Native Status

Natural Setting
Site Type
Dry, rocky slopes, most often along the coastal side of the mountains, frequently on north facing aspect

Part Shade, Sun

Elevation ?
36' - 6201'

Annual Precip. ?
11.5" - 154.9"

Summer Precip. ?
0.18" - 1.88"

Coldest Month ?
39.4° F - 55.1° F

Hottest Month ?
62.3° F - 81.6° F

Humidity ?
0.79 vpd - 32.12 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

Sunset Zones ?
7, 14*, 15*, 16*, 17*, 18, 19*, 20*, 21*, 22*, 23*, 24*

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, Bird Gardens, Butterfly Gardens, Bee Gardens

Nursery Availability
Rarely 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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