Hansen's Northwest Native Plant Database

Northwest Native Ceanothus

Kingdom Plantae – Plants
Subkingdom Tracheobionta – Vascular plants
Superdivision Spermatophyta – Seed plants
Division Magnoliophyta – Flowering plants
Class Magnoliopsida – Dicotyledons
Subclass Rosidae
Order Rhamnales
Family Rhamnaceae – Buckthorn family
Genus Ceanothus L. – ceanothus


Species of this genus native to the Pacific Northwest: Washington, Oregon, California and some Canadian Provinces

Ceanothus L. Ceanothus
Ceanothus cordulatus Kellogg Whitethorn Ceanothus
Ceanothus cuneatus (Hook.) Nutt. Buckbrush
Ceanothus cuneatus (Hook.) Nutt. var. cuneatus Buckbrush
Ceanothus integerrimus Hook. & Arn. Deerbrush
Ceanothus prostratus Benth. Prostrate Ceanothus
Ceanothus pumilus Greene Dwarf Ceanothus
Ceanothus sanguineus Pursh Redstem Ceanothus
Ceanothus thyrsiflorus Eschsch. Blueblossom
Ceanothus velutinus Douglas ex Hook. Snowbrush Ceanothus
Ceanothus velutinus Douglas ex Hook. var. hookeri M.C. Johnst. Hooker's Ceanothus
Ceanothus velutinus Douglas ex Hook. var. velutinus Snowbrush Ceanothus


General Information For This Genus

Click on links at bottom of this page for photos and details of each plant.

Descriptions: Oregon has been favored by nature as the home of several species of Ceanothus in both the eastern and western areas of the state. The most familiar is probably the Blue Blossom (Ceanothus thyrsiflorus), which is native to the southwest coastal region of Oregon and into California. Although it's most outstanding feature is the true blue flower clusters in April through June, this medium to large shrub is also prized for it's year-round glossy dark green leaves.

More common to eastern Oregon is the Snowbrush, Ceanothus velutinus, a smaller evergreen shrub with glossy aromatic leaves, white spikes of flowers and a welcome ability to withstand the cold.

Throughout western North America we find the Red Stem Ceanothus, a deciduous shrub that grows smaller than the Blueblossom but slightly larger than Snowbrush. It has white blossoms April through June, fruit in June and July. It's larger leaves are pleasant but the red stems that show to great advantage in the winter landscape after the leaves have fallen are it's most outstanding quality.

Blueblossom and Snowbrush leaves are oval-shaped 1 1/2 to 2 1/2 inches long, shiny dark green with serrated edges and 3-veined from the base. Leaves of the Red Stem variety are larger, grass-green and slightly hairy. Flowers are borne in dense clusters, very blue up to 3 inches long for C. thrysiflorus and white up to 5 inches long in C. velutinus. Red Stem flowers are flat clusters approximately 3 inches across and looser than the evergreens. The fruit of all three species is small 3-lobed filed with tiny dark seeds which have a hard coat.

This family of shrubs performs a valuable ecological service in fixing large amounts of nitrogen in the soil. They do this through a symbiotic association with a bacteria which inhabit their roots. This ability is currently being studied as a major player in land reclamation after forest fires.

About.com offers this bit of info:

Nitrogen in the soil is the most important element for plant development. It is required in large amounts and must be added to the soil to avoid a deficiency. Nitrogen is a major part of chlorophyll and the green color of plants. It is responsible for lush, vigorous growth and the development of a dense, attractive lawn. Although nitrogen is the most abundant element in our atmosphere, plants can't use it until it is naturally processed in the soil, or added as fertilizer.

Now, most native plant gardeners are not afficionados of the 'lawn,' but the same dynamics exist with practically every other plant on the earth. Keeping a few ceanothus growing in your yard will take care of the nitrogen requirements your other plants may need. If you have some squirrels around, they'll help with mixing the soil in the landscape--less work for the friendly gardener!

Habitat and Geographic Range: Generally speaking, most evergreen Ceanothus are not sufficiently cold-hardy for the high desert temperatures of eastern Oregon. However, they are perfectly suited for the milder lower elevations in eastern Oregon and the western side of the state. One thing all varieties agree upon is the drought of summer. They must have well-drained soil: standing water will quickly give rise to root-rot. We often see them in soil low in organic matter.

In North America, Red Stem is found from the Siskiyou Mountains of northern California to the southern areas of British Columbia, including Vancouver Island. It's range reaches to the east in mountainous sites to western Montana where is has been reported at 2,400 feet. It also occurs in northern Michigan, California to 4,000 feet, Idaho, Minnesota, Montana, Oregon and Washington. Red Stem ceanothus is a prominent component of seral brush field communities as well as those of mixed conifers.

In mountain ranges, we see it mostly in areas of Ponderosa pine (Pinus ponderosa), mixed conifers and Western Hemlock (Tsuga heterophylla). Common companions are Ninebark (Physocarpus malvaceus), Oceanspray (Holodiscus discolor), Rocky Mountain Maple (Acer glabrum), Grand Fir (Abies grandis), Scouler's Willow (Salix scouleriana), Saskatoon (Amelanchier alnifolia), Western Red Cedar (Thuja plicata), Douglas Fir (Pseudotsuga menziesii), Snowberry (Symphoricarpos albus), Thimbleberry (R. parviflorus), and Bitter Cherry (Prunus emarginata). In both the Cascade Range and the Rocky Mountains it is found primarily in the Ponderosa Pine (Pinus ponderosa) zone and in parts of the mixed conifer and Western Hemlock zones.

In the forest succession studies, Red Stem Ceanothus/Ninebark groups are prominent as post-fire structural components. They are associated with early- or mid-seral stages of forest succession. Red Stem Ceanothus particularly is prominent colonizer after fire or timber harvest. When the tree canopy becomes denser this shrub is more sparse, often giving way to Oceanspray and Chokecherry (Prunus virginiana) though it is often 15 years before it recedes to the brush field areas.

Uses of Plant: Landscape: All 3 of the ceanothus under discussion here are excellent landscape plants. Their needs are few: good drainage and occasional rain after they are established. Poor soil is fine with them all, no fertilization required.

Red Stem Ceanothus is clearly intolerant of shade, but Snowbrush will tolerate partial shade (although it does prefer sun) and Blueblossom is much less particular in this regard. All are excellent both inland and oceanside.

The beautiful clear blue of Blueblossom, white clusters of blooms for Snowbrush and attractive dark green leaves of both are desirable features. All bloom abundantly at a young age with fragrant blossoms. Ceanothus sanguineus' red stem bunches are excellent winter beauty. All these shrubs are well-behaved: they can be pruned back to limit growth, they allow trimming into rounded or cushion shapes sheared into hedges, but their natural growth habits are not overwhelming. Left to assume their full growth naturally, they are full and pleasant to the eye.

Reclamation uses: Naturally occurring after fires or timber harvest, Ceanothus curbs erosion and has the very desirable ability of fixing nitrogen in the soil.

Wildlife habitat: An important food and shelter for many wildlife species, and browse for white-tail and mule deer. Red Stem is reported to comprise as much as 1/3 of the winter diet of Rocky Mountain elk. Livestock will also eat Red Stem as do domestic sheep. Birds such as the rufous-sided towhee, western bluebird, Nashville warbler and olive-sided flycatcher, and small mammals such as deer mice, voles and chipmunks find shelter in these shrubs and are fond of the seeds as are insects. Native bees are attracted to the blossoms.

Native Americans make tea from the leaves and flowers. Some species produce better tasting tea than others. A red dye can be made from the roots. The stems make perfect foundations for baskets. The blossoms can be mixed with water to produce a soap. A native custom among some tribes sees a bride and groom shampooing each other's hair with this aromatic mixture as part of the wedding ceremony.

Propagation: Red Stem Ceanothus develops a deep root system that can aid in soil stabilization. This species can be nursery propagated, and has been successfully planted on logged sites, road cuts, and acid mine spoils.

If a large area is to be seeded, the seeds must be heat-treated and sown immediately during late fall rains just before snowfall. The seeds will then stratify naturally in the soil over winter and most will germinate the next spring, although small numbers may continue to sprout for up to 8 years. Sprouts can produce seed by 3 - 6 years of age.

Cuttings and seedlings alike are susceptible to stem rot or "damping off," cold winter temperatures, drought, fungus, heavy competition and herbivores. Those that are still living by the second year will normally survive.

Culture: Ceanothus perform best with little summer watering. Too much water generally causes root rots except in stages of active growth. Late in the season, withhold water to allow the plants to harden off before winter sets in. Until established, deep watering is required. After the plants are comfortable in their surrounds, minimal watering is recommended.

Do not be mislead into thinking lots of water and fertilizer will make a better plant. In the case of Ceanothus, water deeply until the plant is firmly rooted in the well-drained soil and then water sparingly, if at all, after the establishment period is over. Fertilizer is not welcome to Ceanothus and may actually shorten their life-span.

Red Stem prefers full sun as does Snowbrush which will take some shade and Blueblossom will take more shade.

Pruning can be done at any time, but should be limited by fall as it usually promotes new growth which may be damaged unless it has time to mature before the cold season sets in. Of course, pruning after the blooming period is desirable so the beautiful blossoms and their fragrance can be appreciated.

As an experiment, we planted a 1-gallon Ceanothus thrysiflorus under a large conifer, watered it deeply 3-4 times during the first year and not at all since then. It is now in it's third season since planting, quite strong and sturdy and presented an admirable show of blue blooms this year.

Historical and Special interest: The Oregon Garden trials are testing a range of Ceanothus cultivars, from small to large shrubs. These will be evaluated by variety for rate of growth, length and degree of bloom and sensitivity to cold. The goal is to find which varieties will fare best in Oregon's Willamette Valley.

Origin of botanical name, original discovery info, etc.: Common names are self-explanatory. Also known as New Jersey tea.

A special thanks to the USDA Forest Service Fire Effects Information website, located at http://www.fs.fed.us/database/feis/about.html

Species Information For This Genus

Click on links below for photos and details of each plant.

As yet, not all northwest native ceanothus are covered in this website, though that may be done some time in the future. For now, we have information about only six of our northwest native ceanothus.

Ceanothus cuneatus var. cuneatus (Buck Brush)

A spreading evergreen shrub, rounded to sprawling, reaching 9 - 10' tall at maturity. The evergreen leaves are stiff and somewhat tough and may be slightly toothed along the edges. Abundant white flowers, sometimes tinted blue or lavender. Fruit is a round capsule with horns. Hybridizes easily with similar species, producing varied forms.


Ceanothus integerrimus (Deerbrush, Mountain Lilac)

A deciduous shrub 3 - 13' tall openly branched. Drought-tolerant. The light green leaves are glossy, 1-3" long, ovate. Flowers are white or blue or (rarely) pink. Fruit is a sticky capsule that ejects seed when split.

Photo credit: Franz Xaver

Ceanothus prostratus (Mahala Mat)

This evergreen shrub is very low growing, forming a mat up to 8 feet wide. Small leaves are tough and leathery with sharp teeth along the edges. Flowers are small clusters of deep blue to lavendar tight to the stems. Very nice groundcover.

Ceanothus sanguineus (Red Stem Ceanothus)

A deciduous shrub growing to 9 feet at maturity. Native to western North America from British Columbia to Montana to far northern California; it is also known from Michigan. As do some other Ceanothus, this one requires fire for reproduction and proliferation. The seeds become active with heat and the plants quickly fill in spaces left by wildfires. Clusters of white flowers are about 4 inches long. An important food source for elk and also browsed by livestock. Seeds are also enjoyed by many kinds of animals.

Ceanothus thyrsiflorus (Blueblossom, California Lilac) The queen of wild evergreen lilacs, Blueblossom reigns with grace and majesty from southwestern Oregon to southern California (USDA zones 8-10). When mature, it often reaches 20 feet tall in its native habitat of chaparral. Quite tolerant of shade, the blue flowers are outstanding. They can also vary from pale blue to white and many shades of blue.
Ceanothus velutinus (Snowbrush)

A medium-tall evergreen shrub from 9-10 to 13 feet when fully grown. It is a colonizing plant which tangles together to make an almost impenetrable thicket. With its aromatic leaves and plentiful long clusters of white flowers, this is an excellent choice for tall hedges. The three-lobed seed pods snap open and shoot the three seeds into the soil where they can lie in wait for centuries until a wildfire comes along to scarify them. Consequently, there is little bother by volunteers. However, the seeds can be caught and scarified manually to produce new plants.

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