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. The list of species below is divided into their uses as groundcovers or shrubs. California Wild Lilac grows in zones 5-9 and 14-24. To find your zone, click here: Zone Map.
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Ceanothus Groundcover Varieties
Ceanothus 'Centennial'
2 feet tall and 10 feet wide, with shiny dark green leaves and dark blue flowers.
Ceanothus gloriosus 
(Point Reyes Ceanothus)
1.5 feet tall, 14 feet wide with dark green shiny leaves and light blue flowers
Ceanothus gloriosus 'Anchor Bay'
1.5 feet tall and 7 feet wide with dense leaves and blue flowers.
Ceanothus gloriosus
​'Heart's Desire'
1 foot tall and 7 feet wide, bronzy green leaves and pale blue flowers.
Ceanothus griseus horizontalis
​(Caramel Creeper)
Not good in zone 18; 2ft. tall, 10 feet wide, green leaves with light blue flowers. 
Ceanothus griseus horizontali 
​'Diamond Heights'
​1 foot tall, 6 feet wide, green variegated leaves, light blue flowers.
Ceanothus grisalis horizontali 'Yankee Point'
3 feet tall, 9 feet wide. Glossy, dark green leaves, blue flowers.
Ceanothus hearstiorum
6 inches tall, 7 feet wide. Medium blue flowers. 
Ceanothus 'Joyce Coulter'
4 feet tall, 11 feet wide. Green leaves, blue spikes of flowers.
Ceanothus maritimus
2 feet tall, 5 feet wide. Grey-green leaves and white to lavender flowers.
Ceanothus maratimus 'Frosty Dawn'
2 feet tall, 5 feet wide, grey- green leaves and dark lavender flowers.
Ceanothus maratimus 'Point Sierra'
3 feet tall, 5 feet wide. Gray-green leaves and violet flowers. 
Ceanothus Shrub Varieties
Ceanothus Arboreus 
(Island Ceanothus)
12-30 feet tall, dark green leaves and blue flowers.
Ceanothus 'Blue Jeans'
8 feet tall/wide with dark green leaves and pale powder blue flowers.
Ceanothus 'Concha'
7 feet tall and wide, dark green leaves and dark blue clusters. 
Ceanothus 'Cynthia Postan'
7 feet tall and wide, dark green leaves and violet-blue flowers.
Ceanothus 'Dark Star'
6 feet tall, 9 feet wide. Dark green leaves and cobalt blue flower clusters.
Ceanothus 'Frosty Blue'
9 feet tall, 10 feet wide. Dark green, dense leaves, sea blue flower clusters. 
Ceanothus impressus 'Vandenburg'
4 feet tall, 5 feet wide. Dark green leaves, cobalt blue flower clusters in spring. 
Ceanothus impressus 'Victoria'
8 feet tall, 11 feet wide. Leaves are green, with deep blue flowers. 
Ceanothus 'Julia Phelps'
7 feet tall, 9 feet wide. Dark green leaves and dark indigo flower clusters. 
Ceanothus 'Ray Hartman'
20 feet tall and wide. Large dark green leaves, blue flower clusters. 
Ceanothus 'Sierra Blue'
12 feet tall, 10 feet wide, green leaves, bright blue flower clusters. 
Ceanothus thyrsiflorus
​'El Dorado'
8 feet tall and wide, Dark green variegated with yellow leaves, blue flowers. 
Ceanothus thyrsiflorus 'Louis Edmunds'
6 feet tall, 20 feet wide. Bright green leaves and sea blue flower clusters.
Ceanothus thyrsiflorus 'Skylark'
6 feet tall and 12 feet wide. Medium green leaves with dark blue blooms.
Ceanothus thyrsiflorus 'Snow Flurry'
10 feet tall, 12 feet wide. Green leaves, pure white clusters of flowers.
Ceanothus 'Wheeler Canyon'
6 feet tall, 8 feet wide. Bright blue flowers with red bracts, narrow, textured leaves.

Caring for and pruning ceanothus shrubs

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. They grow well in full sun but in warmer temperatures appreciate a little afternoon shade. Ceanothus likes well-draining soil, but is otherwise not picky. They do not need to be fertilized. Once established, provide a deep watering about once or twice a month. Provide shelter from frost and strong winds. Ceanothus does not take well to hard prunings, so make sure you choose a species that has the correct measurements for your space. Prune branch tips just after blooms fade, and deadhead as needed. 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.

Propagation

Ceanothus can be propagated either by using cuttings or from seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the cutting method. If you would like to experiment and see what plant you can grow from seed, just keep in mind that it will not necessarily be the same as the parent plant. To propagate your 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:
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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
If you have any questions, comments, concerns, or photos you’d like to add to the gallery, please let me know by sending me a message using the button below!
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