Western Ceanothus naturally grow in temperate climates with hot dry summers and short mild winters providing a modicum of precipitation. So, for the most part, these wild lilacs do not require much water once they are established--or to establish them for that matter. Our rule of thumb is to water them when the soil is on the dry side, whether they inhabit heavy clay soils or sandy ones.
Using the Growing Guide Table
Because the West's wild terrain is so diverse; from the sandy bluffs above the Pacific Ocean to the spreading flats of the San Joaquin Valley, to the 11,000' to 14,000' peaks of the Sierra Nevada Mountains and west to the Sonoran Desert and Great Basin, there will be a Ceanothus suited to your environment. Whenever possible, we've included the original parentage of each wild lilac, hybrid or selection which will offer clues as to what the plant's cultural needs might be. For example, Ceanothus tomentosus whose origins are from the hot, dry interior mountains of southern California, suggests that its baseline cultural preferences would be to be grown in a location similar to the environment to which it is already adapted. Conversely, Ceanothus griseus horizontalis 'Yankee Point', a selection native to the Central Coastal areas of California, may prefer less extreme conditions than C. tomentosus; it is more likely to be tolerant of humidity, slightly more ground water, or shadier conditions. The 'Exposure' category in the table is also derived from the plant's origins. 'Yankee Point', originally from the coast, is more tolerant of shade when grown in a hot, arid inland environment. However, while a plant's origins offers basic clues to its culture, many Ceanothus are widely adaptable to a variety of landscape conditions, as we have also noted in the table. Keep in mind that in the 'Drought Tolerance' category, those plants listed L or M tend to be more tolerant of garden-type conditions.
Telltale Appearances: Euceanothus Versus Cerastes Ceanothus
Another indicator of the culture of each Ceanothus is its outward appearance. The genus Ceanothus is split into two separate sections, the Euceanothus and the Cerastes group. The plants associated with each of these sections is distinct, and so tends to be the habit and required culture as well. Just looking at the plants of the Cerastes Section, with reduced, leathery, widely spaced leaves, one would guess them to be very drought tolerant. Additionally, Cerastes Ceanothus usually has oppositely arranged (exceptions C. insularis, C. verrucosus, C. megacarpus) which are sometimes holly-like, with horned fruit and generally stiffer growth habit. On the other hand, Euceanothus (literally 'True Ceanothus') generally exhibit alternately arranged leaves which are usually broad, glossy or waxy, often dark green and lush-looking. The seed capsules are ridged rather than horned. The flowers tend to be clustered at the tip, uninterrupted by leaves. While there are exceptions, the habit of growth tends to be upright, yet somewhat less stiff than the Cerastes section. The Euceanothus are generally found to enjoy slightly more humidity and moisture than the Cerastes group.
TO SUMMARIZE
- Know each species' original, wild habitat.
- Scrutinize micro-climates in your landscape.
- Match the plant to a micro-climate or landscape conditions roughly similar to its original habitat.
- Don't indulge Ceanothus with too much fertilizer or water, because they are adapted to poor soils and sunny, dry locations.
- Plant and establish them during the wet, cool season.
- Water them when the sub-surface soil is on the dry side.
- Establish them in this way through their second or third dry season. But, if they need water over future dry seasons, by all means give it to them, in the cool of the day, not when the temperatures are scorching.
If, your Ceanothus is to be planted in among existing garden plants:
- Be certain they have compatible water requirements.
- If existing plants receive regular irrigation, plant Ceanothus on top of a mound or swale to increase water drainage.
- Plant on the outskirts or high side of a sprinkler system.
- Look for the symptoms of over-watering: excessive yellowing and dropping leaves, or black spots on leaves or stems, and relocate Ceanothus if necessary.
| Species | Common Name | Derivation/Origins Type | Exposure | Height | Width | Inflorescence Color/Size | Best Features | Drought Tolerance |
| Ceanothus arboreus | Catalina Feltleaf Ceanothus | Coastal California, Channel Islands Euceanothus |
Sun to Partial Sun | 10-30' | 10-15' |
Light Blue to Medium Blue 6" |
Large dark leaves, showy light to medium blue flowers. | Moderate to High |
| Ceanothus 'Blue Cascade' |
Euceanothus | Sun | 6-10' | 8-12' |
Medium Blue 2-3" |
Glossy, bright green leaves with blue, finger like flower clusters | Moderate to High | |
| Cealnothus 'Blue Jeans' | Selection | C. gloriosus porrectus, Central CA Coast Euceanothus |
Sun to Partial Sun | 5-7' | 5-7' |
Light Blue 1" |
Lavender-shaded flowers upon dark green leaves | Moderate to High |
| Ceanothus 'Concha' | Hybrid | C. papillosus roweanus X C. impressus Central CA, inland Euceanothus |
Sun to Partial Sun | 6-8' | 8-12' |
Dark Blue to Violet 2" |
Stunning, profuse electric blue to violet flowers on rigid stems. Tolerant of heavy soils if not over-watered. Cold hardy to 15°F | Moderate to High |
| Ceanothus crassifolius | Hoaryleaf Ceanothus | Interior, Southern California Chaparral Cerastes |
Sun | 5-10' | 5-10' | White 1" | Small, dark, leathery leaves, stiff silver stems, very drought tolerant, good slope stabilizer. Cold hardy to 15°F. | High |
| Ceanothus 'Dark Star' | Seedling Hybrid | C. papillosus roweanus X C. impressus or X C. oliganthus Central CA, Interior CA Euceanothus |
Sun to Partial Sun | 5-6' | 8-10' | Dark Blue to Violet 2" | Showy rounded flower clusters magenta in bud to dark blue/violet. Compact shrub, heavy soils okay, if not over-watered. Tolerates temperatures in the teens. | Moderate to High |
| Ceanothus 'Frosty Blue' | Hybrid | C. impressus X ? Central, Northern Coastal CA, Euceanothus |
Sun to Partial Sun | 6-9' | 8-10' | Medium Blue 4" | Medium blue, frosted flowers with dark green, small leaves. Heavy soils okay. Highly recommended. | Moderate to High |
| Ceanothus gloriosus 'Emily Brown' | Selection | C. gloriosus ssp. exaltatus Central CA Coast Cerastes |
Sun to Partial Sun | 2-3' | 6-8' | Light Blue 1" to Medium Blue 4" | Pretty mounding, holly-leafed ground cover with light blue rounded flower clusters. Hardy. Tolerates high temperatures, blasting sun. Cold hardy to 15°F. | Moderate to High |
| Ceanothus griseus horizontalis | Carmel Creeper | Central CA Coast Euceanothus |
Sun to Partial Sun | 1-3' | 8-12' | Light Blue to Medium Blue 4" | Dark green, dense ground cover. Flowers are long & abundant and milky light blue. Culturally versatile. Okay in heavy soils. Cold hardy to 15°F. | Moderate to High |
| Ceanothus griseus horizontalis 'Yankee Point' |
Selection | griseus horizontalis Central CA Coast Euceanothus |
Sun to Partial Sun | 2-3' | 8-12' | Light Blue to Medium Blue 4" | Dark green, dense ground cover. Flowers are long & abundant and medium sky blue. Adaptable. Okay in heavy soils. Cold hardy to 15°F | Moderate to High |
| Ceanothus griseus 'Louis Edmunds' | Selection | griseus Central CA Coast Euceanothus |
Coastal Sun, Partial Sun, Shade | 6"-1' | 6' | Dark Blue | Extremely prostrate, dark leaves, electric blue flowers. Protect from harsh sun inland. Heavy or sandy soils okay. | Moderate |
| Ceanothus 'Heart's Desire' | Euceanothus | Sun to Partial Sun | 4-6' | 4-6' | Medium Blue | Moderate | ||
| Ceanothus impressus |
Santa Barbara Ceanothus | Central CA Coast Euceanothus |
All (Sun, Partial Sun, Shade) | 8-10' | 8' | Medium Blue 2" | Denim colored flowering clusters on dull, dark green leaves. Cold hardy to 15°F. | Moderate to High |
| Ceanothus 'Joyce Coulter' | Hybrid | C. papillosus roweanus X C. griseus horizontalis ? Central CA, inland Euceanothus |
Sun to Partial Sun | 3-5' | 6-8' | Medium Blue 3-5" | Electric blue, long-blooming flowering show. Tolerant of garden conditions. Blooms well in shade. Good for long, narrow spaces. Cold hardy to to 15°F | Low to High |
| Ceanothus 'Joan Mirov' | Hybrid | C. foliosus X C. griseus Coastal and Interior CA Euceanothus |
Sun to Partial Sun | 3-5' | 8-10' | Dark Blue | Low to Moderate | |
| Ceanothus leucodermis |
Chaparral Whitethorn |
California Chaparral, Foothill Communities Euceanothus |
Sun to Partial Sun | 10-15' | 10-15' | White to Pale/Light Blue 6" | Waxy, oval, light green leaves on stiff branches foil beautiful magenta buds turning to pale blue flowers. Deep rooted, good for erosion control. Cold hardy to at least to 15°F. | High |
| Ceanothus maritimus | Maritime Ceanothus | Central CA Coast Cerastes |
Coastal Sun, Partial Shade, Inland Shade | 1-3' | 3-8' | White to Light Blue 1" | Cascading small- leaved foliage sports white to lavender blue flowers. Great for rock gardens or slopes. |
Low to High |
| Ceanothus maritimus 'Point Sierra' | Selection | C. maritimus Cerastes |
Sun to Partial Sun | 1-3' | 3-5' | Purple 1" | More heat and sun-tolerant than true species. | Low to Moderate |
| Ceanothus megacarpus | Big-pod Ceanothus | Southern CA Coast Cerastes |
Sun to Partial Sun | 10-12' | 8-10' | White 1" | Small, dark, leathery leaves, silver stems with small white flower clusters. Deep rooted, good for wildlife habitat, slope stabilization | High |
| Ceanothus oliganthus | Hairy Ceanothus | Central to Southern CA, Inland Chaparral Euceanothus |
Sun to Partial Sun | 8-12' | 6-10' | Medium to Dark Blue to Violet | Beautiful flowers range from mid-blue to violet. Shiny small dark green leaves. Tolerant of heat, drought, steep slopes. Pretty! Cold hardy to 15°F. | Moderate to High |
| Ceanothus 'Owlswood Blue' | Selection | C. arboreus X ? Channel Islands, Coastal CA Euceanothus |
Sun to Partial Sun |
8-10' |
10-12' | Medium Blue to Dark Blue 4" | Showy inflorescences on treelike shrub with dark, glossy, broad leaves. Okay in shade or Partial Sun and heavy soils. | Moderate to High |
| Ceanothus ramulosus | Coast Ceanothus | Northern CA Coast Cerastes |
Sun to Partial Sun | 8' | 6-8' | White to Light Blue 1" | Lavender to pale blue to white flowers on strange, twisting stems with small spaced leaves. Heavy soils okay with infrequent irrigation | High |
| Ceanothus 'Ray Hartman' | Hybrid | C. griseus X C. arboreus ? Coastal CA Euceanothus |
Sun to Partial Sun | 12-20' | 15-20' | Medium Blue 6" | Beautiful shrub or small tree with long medium blue flower clusters. Okay for shade, assorted soils. | Low to Moderate |
| Ceanothus rigidus 'Snowball' | Selection | C. rigidus Monterery Ceanothus Cerastes |
Sun to Partial Sun | 4-6' | 3-5' | White 1" | Good for hot, sunny slopes. Tightly clustered white flowers cover holly-like leaves. | Moderate to High |
| Ceanothus spinosus | Greenbark Ceanothus | Central, California Coasts, So. California Inland Euceanothus |
Sun to Partial Sun | 6-12' | 10-15' | White to Light/Medium Blue 6" | Long inflorescences usually light to medium blue on light green leaves. Green trunk. Deep rooted, good for hot sunny slopes. Cold hardy to at least to 15°F. | High |
| Ceanothus thyrsiflorus 'Skylark' | Selection | C. thyrsiflorus Central to Northern CA Coast Euceanothus |
Sun to Partial Sun | 3-5' | 3-5' | Dark Blue 2" | Dark green glossy leaves with very dark blue flowers. Relatively garden tolerant | Low to Moderate |
| Ceanothus thyrsiflorus 'Snow Flurry' | Hybrid | C. thyrsiflorus X ? Central to Northern CA Coast Euceanothus |
Sun, Partial Shade, Inland Shade | 8-10' | 10-12' | White 6" | Dark green glossy leaves with long, pretty greenish white flower clusters that never brown on the stem. Exceptional. Heavy soils okay. | Low to Moderate |
| Ceanothus tomentosus | Woollyleaf Ceanothus | Southern CA Inland, Chaparral Euceanothus |
Sun to Partial Sun | 6-10' | 8-10' | White to Luminous Blue 2" | Variably colored white to blue flower clusters on shiny, dark green foliage. Great for slopes, all soils okay. Excellent. Cold hardy to 15°F | Moderate to High |