Ceanothus

( see - an - NOE - thus )

At-A-Glance Information

These shrubs turn entire hills in the Western United States blue in winter and springtime. Also called California Wild Lilac, Soap Bush or Buckbrush, this group of bushes and groundcovers is mostly native to California, though some species come from the Eastern United States, Rocky Mountain Range, Northwest, and Mexico. Flowers come in all shades of blue and white, are somewhat fragrant and bloom from the middle of spring through winter. The shrubs are generally evergreen but some will lose their leaves in colder weather. These shrubs will attract birds, butterflies, hummingbirds and bees to your garden.

ceanothus Species and Varietals

The genus Ceanothus includes about 50-60 species, and is a member of the family Rhamnaceae. California Wild Lilac grows in USDA hardiness zones 7-10 or Sunset growing zones 5-9 and 14-24. To find your zone, click here: Zone Map.

Ceanothus americanus (New Jersey Tea, Jersey Tea Ceanothus, Red Root, Mountain Sweet, Wild Snowball)
This species forms a shrub to between 18 and 42 inches tall at maturity. It survives for about 15 years in the landscape before needing to be replaced. Flowers are white to light pink in color, and bloom in late spring through summertime, peaking in July and August. This species was once used as a tea substitute. The species is native to North America.
Ceanothus arboreus (Feltleaf Ceanothus, Island Ceanothus, Island Mountain Lilac)
This is the largest member of the California Lilacs, and produces glossy dark green foliage. Flowers are pale blue to white. Feltleaf Ceanothus is native to the Channel Islands, California and Guadalupe Island, Mexico. Plants reach up to 12-36 feet tall when mature. 
'Cliff Schmidt'
A compact form with deep blue flowers.
'Owlswood Blue'
To 10 feet tall with blue flowers.
'Powder Blue'
Also called Compact Felt Ceanothus; with powder blue blooms.
'Trewithen Blue'
Very dark blue flowers and green leaves.

Ceanothus confusus (Rincon Ridge Ceanothus)
This species is endemic to the mountains of the San Francisco Bay Area, California. It forms a low, spreading shrub to just under 4 feet wide and 0.5-1.6 feet tall. Flowers are blue and bloom in late spring and summertime. 

Ceanothus cuneatus (Buckbrush, Wedgeleaf Ceanothus)
This species of Ceanothus is native to Oregon, California, and northern regions of Baja California, Mexico. It grows in chaparral landscapes, forming a spreading bush up to 10 feet tall when mature. Leaves are evergreen and stiff, and flowers are white and tiny. 

Ceanothus cyaneus (San Diego Buckbrush, Lakeside Ceanothus)
This species is native to San Diego County, California, and forms an evergreen open shrub that reaches up to 10 feet tall when mature. Leaves are dark green and smooth with hairy undersides. Flowers are deep or bright blue and bloom in April through June.

Ceanothus fendleri (Fendler's Ceanothus, Fendler's Buckbrush, Deer Brier)
This species grows in pine forests in northern Mexico, Arizona, New Mexico, Texas, Utah, Colorado, Wyoming and South Dakota. It reaches over 3.3 feet tall when mature, and has green leaves. Flowers are cream colored to white and are held in thick clusters, particularly on older stems. 
Ceanothus gloriosus (Point Reyes Ceanothus)
Native to coastal areas in the San Francisco Bay area, this shrub reaches up to 6 feet tall at maturity. Leaves are evergreen and flowers are borne in small clusters. Blooms can be bright blue to purple in color. There are many cultivars of this species, including:
'Anchor Bay'
​​1.5 feet tall and 7 feet wide with dense leaves and blue flowers.
'Heart's Desire'
​​1 foot tall and 7 feet wide, bronzy green leaves and pale blue flowers.
Ceanothus griseus (Carmel Ceanothus, Carmel Creeper)
This species is native to California, where it grows in chaparral and coastal scrub landscapes. It can reach up to 6 feet tall when mature, though it can also take a less erect form and be a bit shorter. Flower inflorescences are densely packed with small blue-purple flowers.
'Carmel Creeper'
​2 feet tall and 10 feet wide. Green leaves with light blue flowers. 
'Centennial'
​Also known as 'Carmel Creeper'.
'Diamond Heights'
​​1 foot tall, 6 feet wide, green variegated leaves, light blue flowers.
'Louis Edmonds'
Vigorous with blue flowers; tolerant of part shade and good for coastal gardens.
'Point Sal'
A cultivar with green leaves and blue-purple blooms.
'Yankee Point'
3 feet tall, 9 feet wide. Glossy, dark green leaves, blue flowers.

Ceanothus hearstiorum (Hearst Ranch Buckbrush, Hearst's Ceanothus)
This species is endemic to California, and reaches up to 6 inches tall and 7 feet wide. Flowers are a medium-blue. Leaves are green and have a distinct cupped, rippled surface.
Ceanothus spp. Hybrids (Hybrid Ceanothus)
This group of Ceanothus shrubs are hybrids between established species, each bred to perform well in the landscape.
'Blue Jeans'
8 feet tall/wide with dark green leaves and pale powder blue flowers.
'Cynthia Postan'
7 feet tall and wide, dark green leaves and violet-blue flowers.
'Dark Star'
6 feet tall, 9 feet wide. Dark green leaves and cobalt blue flower clusters.
'Frosty Blue'
9 feet tall, 10 feet wide. Dark green, dense leaves, sea blue flower clusters. ​
'Joyce Coulter'
4 feet tall, 11 feet wide. Green leaves, blue spikes of flowers.
'Julia Phelps'
7 feet tall, 9 feet wide. Dark green leaves and dark indigo flower clusters. ​
'Ray Hartman'
20 feet tall and wide. Large dark green leaves, blue flower clusters. ​
'Sierra Blue'
12 feet tall, 10 feet wide, green leaves, bright blue flower clusters. ​
'Vandenberg'
4 feet tall, 5 feet wide. Dark green leaves, cobalt blue flower clusters in spring. ​
'Victoria'
8 feet tall, 11 feet wide. Leaves are green, with deep blue flowers. ​
'Wheeler Canyon'
6 feet tall, 8 feet wide. Bright blue flowers with red bracts, narrow, textured leaves.

Ceanothus maratimus (Maritime Ceanothus)
​This species of Ceanothus is native to San Luis Obispo County in California, and is a spreading or upright shrub that reaches under 3 feet tall when mature. Bark is reddish and ages to gray. Leaves are evergreen, shiny on top and woolly underneath. Leaf margins are typically curled under and are sometimes toothed. Flowers are deep blue to almost white. Popular cultivars include 'Frosty Dawn' (2 ft. tall, 5 ft. wide, with dark lavender blooms), and 'Point Sierra' (3 ft. tall, 5 ft. wide, violet flowers).

Ceanothus oliganthus (Hairy Ceanothus, Hairy-Leaf Ceanothus, Jimbrush)
Native to California and Baja California, this species grows in chaparral landscapes. It forms a large, erect shrub up to 10 feet tall with evergreen leaves. Flowers are light to deep blue-purple and bloom between the months of April and May.

Ceanothus parviflorus (Littleleaf Ceanothus, Littleleaf Whitethorn)
This deciduous species forms a shrub with a flat top, and grows to reach up to 3 feet tall with a spread of 8 feet. Flowers bloom in various shades of blue. Leaves are small and green. This species is native to Sierra Nevada mountain range in California.

Ceanothus prostratus (Prostrate Ceanothus, Pinemat, Mahala Mat)
This species is native to the Pacific Northwest of the United States, where it grows in coniferous forests and open plateaus. It grows to be less than a foot tall when mature with a spread of about 10 feet. Leaf margins have sharp teeth. Flowers are blue, purple, or lavender and bloom between April and June.

Ceanothus pumilus (Dwarf Ceanothus, Siskyou Mat)
This species is native to mountains in southern Oregon and northern California, and grows in coniferous forest and chaparral landscapes. It forms a low-lying shrub a foot or two tall and 8 feet wide. Flowers can be blue, lavender, or white and leaves are glossy and green with smooth margins.
Ceanothus thyrsiflorus (Blueblossom, Blue Blossom Ceanothus, California Lilac, Mountain Lilac)
​This species of Ceanothus is native to California and Baja California. It forms an erect shrub or small tree to 10 feet tall. Leaves are evergreen, and flowers are pale blue to deep blue. Cultivars of this species are listed below:
'Blue Mound'
​To about 4.5 feet tall with light blue to lavender flowers.
​'El Dorado'
8 feet tall and wide, Dark green variegated with yellow leaves, blue flowers. 
'Skylark'
6 feet tall and 12 feet wide. Medium green leaves with dark blue blooms.
'Snow Flurry'
10 feet tall, 12 feet wide. Green leaves, pure white clusters of flowers.

Ceanothus velutinus (Snowbrush Ceanothus, Red Root, Tobacco Brush, Sticky Laurel)
These shrubs reach up to 13 feet tall when mature, and form colonies of individuals that tangle together to form thickets. Leaves are aromatic and evergreen, and flowers are white to cream-colored, blooming in late spring and summer. This species is native to an area that ranges from British Colombia down to California and Colorado in North America.

Caring for ceanothus

California Lilac is easy to grow, drought-tolerant, and fast-growing, making them an easy choice for Western gardens. Plant them in late fall to early wintertime between 3 and 15 feet apart (spacing is dependent on the species grown). For hedge species, space plants around 6 feet apart. They appreciate a space that is sheltered from frost and strong winds, especially when plants are young. Ceanothus grow well in full sun but in warmer temperatures appreciate a little shade. Ideally, they should be getting between 6 and 8 hours of sun each day with some late afternoon shade. Ensure that soil is well-draining, rich in nutrients, and has a pH of between 4.5 and 7.0 (acidic to neutral). If local soils are particularly poor in nutrients or do not drain well, make sure to amend the planting area with plenty of organic compost before installing. Apply a layer of mulch around the planting area to suppress weed growth, maintain consistent soil temperatures, and to increase soil moisture retention. Water new plantings regularly as they establish in the landscape. Once established, provide a deep watering about once or twice a month.

Ceanothus shrubs do not need to be fertilized. These shrubs do not take well to hard prunings, so make sure to choose a species that has the correct measurements for the allotted space. Prune branch tips just after blooms fade, and deadhead as needed. Remove dead or weak growth, as well. Ceanothus shrubs should be pruned during the dry months of the year. They are very susceptible to Apricot canker if they are pruned in wet weather. Do not leave stubs after pruning; these are easily infected. Larger species can be pruned into trees, beginning when they are young. Select a strong, central leader branch and gradually remove lower branches over several years, starting after the second year. Once a main trunk is well established, shorten top branches to encourage an upright, stocky form and control for height. The life span of Ceanothus shrubs varies widely depending on the species, but they are generally considered long-lived woody perennials. With proper care, many varieties can live for upwards of 25-30 years or longer in the landscape before needing to be replaced.

Propagation

Ceanothus shrubs are best propagated by using cuttings. Growing Ceanothus from harvested seed is possible, though it is a difficult process and seeds can be difficult to get to germinate, and it is a process better suited for more experienced horticulturalists. To propagate your California lilac shrub, follow the instructions below:

Propagating Ceanothus by Cutting
  1. Gather your materials. You'll need a clean, sanitized, sharp pair of garden shears, rooting hormone, a pencil, and a 3-inch pot filled with well-draining compost or other organic material. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand.
  2. In summer or fall, choose the plant that you'd like to propagate. Ensure that this plant has had a good watering the night before, as this will improve the chances your cutting will take root. Cut one or more 6 inch portion(s) of the end of a softwood branch and strip off the lower half's leaves. Make a hole in your planting medium by pushing your pencil into the soil. Dip the end of the stem in rooting hormone, and plant it in your pot. Fill in soil around the cutting to support it, but do not pack it down too much.
  3. Moisten with water, and ensure that the pot has good drainage. Your pot should be kept in warm, sunny conditions indoors (and not in direct sunlight). Water whenever your soil is dry under the top layer. Deciduous types should take about four to six weeks to start rooting, and evergreen varieties take about a year. When you notice new growth on your propagated shrub, you'll know you have roots.
  4. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, for two to three years, when you can transplant it to its new home in your garden.

Problems and Pests

Ceanothus shrubs typically don't have many pest or disease issues, but can suffer from the following from time to time:
  • Aphids
  • Scale
  • Powdery Mildew
  • Root and Crown Rot
  • Oak Root Fungus
  • Apricot Canker
For more information on how to treat and manage these issues, consult the links below:
​

Gallery

Bees love Ceanothus shrubs. When they are in bloom, they will be covered with little pollinators!
Use California Lilac as a covering for walls, fences or foundations.
Certain climbing varieties of Ceanothus are great for covering arbors and trellises.

Videos

Why you should plant California Lilac in your yard.
All about California Lilac.
Pruning Ceanothus shrubs.
Bees love Ceanothus!

Resources

Managing Pests in Gardens: Trees and Shrubs: Ceanothus
Ceanothus: California Lilac
Wikipedia: Ceanothus
How to Grow and Care for Ceanothus (California Lilacs)
The New Sunset Western Garden Book: The Ultimate Gardening Guide (2012) - Pages 226 - 228, Ceanothus