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Ceanothus arboreus

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About Island Ceanothus (Ceanothus arboreus) Ceanothus arboreus is a species of shrub endemic to California, especially to the Channel Islands. It is known commonly as feltleaf ceanothus. It is a species of what are sometimes called California lilacs, and may be referred to as the California mountain lilac or island mountain lilac. It is one of the tallest of the genus, growing up to 25-30 ft. in height, bearing glossy dark green leaves which are leathery or felt-like on their undersides. It is sometimes planted as a fast-growing ornamental for its showy bright blue flowers, which grow in plentiful panicles, or bunches, of tiny five-lobed blossoms. Some varieties and cultivars have light, powder blue blooms, and others bear darker blue flowers. One named variety is known as 'Owlswood Blue'. The species is used as a parent in popular ornamental hybrids such as 'Ray Hartman'. The fruits are three-lobed, triangular capsules. As a native of dry California, the plant is drought-tolerant and may be found in chaparral ecosystems. It has a reputation for being short lived, but life span is improved by not overwatering, withholding summer water and replicating natural conditions as much as possible.
Plant Description
Plant Type

Max. Height
20 - 30 ft (6.1 - 9.1 m)

Max. Width
10 ft (3.0 m)


Fragrant - Pleasant

Growth Rate


Flower Color

Flowering Season
Spring, Winter

Native Status

Natural Setting
Site Type
Dry slopes among chaparral, primarily on the Channel Islands. Does best near the coast (within about 20 miles) where island conditions can be replicated.


Elevation ?
4' - 2066'

Annual Precip. ?
12.1" - 19.2"

Summer Precip. ?
0.14" - 0.32"

Coldest Month ?
46.3° F - 57.1° F

Hottest Month ?
63.0° F - 72.9° F

Humidity ?
1.34 vpd - 16.94 vpd

Soil Description
Tolerates a variety of soils but does best and lives longest in well drained soil

Soil PH
6.0 - 8.0

Fast, Medium

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

Sunset Zones ?
7, 8, 9, 14*, 15*, 16*, 17*, 19*, 20*, 21*, 22*, 23*, 24*

Companion Plants
Ideal companions are other island plants such as Catalina Cherry (Prunus ilicifolia ssp. lyonii), Island Mallow (Malva assurgentiflora), Island Live Oak (Quercus tomentella), and Island Ironwood (Lyonothamnus floribundus ssp. aspleniifolius), but any chaparral plants will also work.

Wildlife Attracted
Insects, especially bees, are attracted to the flowers. Birds such as quail and towhees are attracted to the seeds. Plants in the Ceanothus genus are host plants to the Spring Azure, Echo Blue, Pacuvius Duskywing, California Tortoiseshell, Pale Swallowtail, and Hedgerow Hairstreak butterflies.

Landscaping Information
Ease of Care
Very Easy

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

Very Popular

Max. Summer Water ?
No Summer Water
No Summer Water
Keep moist

Organic with Rocks

Prune in dry season to reduce chance of infection through the wound

Pest Control
Ceanothus are susceptible to aphids, white fly and a stem gall.

Propagation ?
Because Ceanothus species hybridize freely, propagation by cuttings is usually recommended in order to obtain a true representative of a given taxa.  For propagating by seed: Hot water; then 2 mos. stratification may improve germination.

Common uses
Bank Stabilization, Bird Gardens, Butterfly Gardens, Bee Gardens

Nursery Availability
Commonly Available

Other Names
Botanical Names
Ceanothus arboreus var. glabra

Common Names
Feltleaf Ceanothus

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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