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Calistoga Ceanothus
Ceanothus divergens

About Calistoga Ceanothus (Ceanothus divergens) Ceanothus divergens, commonly known as Calistoga ceanothus, is a rare evergreen shrub in the Rhamnaceae family. It is found in just a few locations in the Northern California Coast Ranges of California at altitudes of less than 500 meters. Due to its rarity in the wild, it is included on CNPS list 1b.2. This plant has a growth habit described as ascending to erect and may attain a height of 3 ft. The plant's preferred habitat is on shrub-covered, rocky, volcanic slopes. The hermaphrodite blue or purple flowers bloom in April and May. The sub-globose fruits are five to six millimeters in diameter. This plant is rarely seen in cultivation and not often available for sale.
Plant Description
Plant Type

Max. Height
1.6 - 3 ft (0.49 - 0.9 m)

Max. Width
3 ft (0.9 m)

Fragrant - Pleasant

Growth Rate


Flower Color
Blue, Purple, Red

Flowering Season
Spring, Winter

Native Status
Natural Setting
Site Type
Dry rocky chaparral slopes of Marin, Sonoma and Napa Counties


Elevation ?
24' - 4310'

Annual Precip. ?
15.6" - 61.3"

Summer Precip. ?
0.23" - 0.83"

Coldest Month ?
42.1° F - 49.7° F

Hottest Month ?
62.1° F - 74.3° F

Humidity ?
0.48 vpd - 22.04 vpd

Soil Description
Typically rocky soils


Cold Tolerance(° F)
Tolerates cold to 10° F

Companion Plants
Use with any chaparral plants of the northern Coast Ranges

Landscaping Information
Ease of Care
Moderately Easy

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

Seldom Used

Organic with Rocks

Propagation ?
For propagating by seed: Hot water; then 2-3 mos. stratification may improve germination.

Common uses
Bank Stabilization, Deer Resistant, 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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