CEANOTHUS: Wild Lilac
Do you have a spot that gets no summer water? Is it in full sun or partial shade, with quick drainage, maybe even on a slope? Ceanothus could be the perfect answer to what is often a troublesome spot for gardeners! Even if you don’t have a spot like this in your garden, our native wild lilac is worthy to add to your collection of container plants.
Ceanothus is a plant known to many, because of the striking blue flowers that attract both bees’ and gardeners’ attention from a long distance away. There are about fifty varieties native to North America; most are California natives (sometimes exclusively), only a handful native to Oregon. They self–hybridize fairly readily, so there are now many cultivars (C. thrysiflorus ’Oregon Mist’ for example) and hybrids available in the retail trade – there are Ceanothus of all shapes and sizes to choose from!
Our native wild lilacs range in form from groundcover to large shrub or small tree; deciduous and evergreen; flowers of creamy white to bright cobalt blue. What they all have in common, however, is their need for excellent drainage, lack of summer watering and nutritionally lean soil. Overwatering and overfeeding will shorten the lifespan of your Ceanothus considerably. In their native habitat, they reside in dry forests, dry rocky slopes, dry wooded canyons.
Get the idea? This is the kind of setting you need to try to replicate to make your Ceanothus happiest. But oh so worth the effort! Spring and summer, the slightly fragrant flowers are a magnet for hummingbirds, butterflies and especially bees (if you’re allergic, place the plant in a far corner of the garden?), and the attractive blooms will make you the envy of all your gardening friends. Evergreen varieties have the added benefit of seeds and cover for songbirds, too!
Here’s a sampling of the Oregon wild lilacs (disclaimer: not all of these are readily available):
C. cuneatus – buckbrush
Small evergreen gray–green leaves and spiny, branching habit to about 6’. Flowers are white to light blue, appearing in mid–spring to early summer.
C. integerrimus – deer brush
Deciduous shrub to 12’ with thin leaf blades and tiny white or blue flowering panicles in the late spring / early summer. While it still needs well–drained soil, this one can tolerate a bit more water than some of the others. (Photo credit Franz Xaver)
C. prostrates – prostrate ceanothus
This one only grows to about 2" tall, forming mats as large as 6’ across, often rooting from branches that touch the ground. Small, thick oval leaves are spiny along their edges, almost like miniature holly leaves; the flowers that appear in late spring to mid–summer are light to deep blue clusters about 1” across. Note: while this is a lovely trailing shrub, it is a challenge to grow west of the Cascades.
C. pumilus – Siskiyou mat, dwarf ceanothus
Evergreen, mat–forming groundcover, spreading to 6’. Leaves are dark green, wedge–shaped. Flowers are small umbels of white, lavender or blue, appearing in late spring to early summer. Needs especially fast–draining, rocky or sandy soil, and more sun than not. (Photo Credit Paul Slichter)
C. sanguineus – redstem ceanothus, Oregon tea tree
Deciduous shrub, with striking purplish stems and panicles of fragrant white flowers, blooming late spring to mid–summer. Upright growth to 10’. Not as showy as some other varieties, perhaps, but one that is a bit more well–suited to our climate, as it’s native to areas west of the Cascades. (Photo Credit Walter Siegmund)
C. thrysiflorus – blueblossom
Evergreen shrub or small tree to 18’. Leaves are dark green on the upper surface, lighter green beneath. Flowers are tight panicles up to 6" long in light to dark blue, blooming from mid–spring to early summer, and sometimes again in the fall. This is the best–known (and easiest to grow here west of the Cascades) of the native Ceanothus, and typically the most widely available (both as straight species and in the form of its cultivars). This isn’t the best choice if you’re east of the Cascades. (Photo Credit: Wikimedia Commons Barra)
C. velutinus – snowbrush, mountain balm
Spreading evergreen shrub to 10’ tall and 6’ (or more) wide. The foliage carries a distinct, resin–like fragrance that can be pleasant in the warmth of summertime, when planted near a patio or other outdoor seating area. The flowers too are fragrant, held in dense clusters of white during the summer.
Family: Rhamnaceae (Buckthorne)
Common Name: Wild Lilac
Origin: Of the fifty or so species that are native to North America, there are a little over a half–dozen native to Oregon. (Many others are exclusively native to California, which is why the common name is often known as California Lilac.)
Characteristics: There are evergreen and deciduous species of Ceanothus. Of the evergreen varieties, leaves tend to be small, rounded to oval, toothed and somewhat leathery in texture, usually dark green. Leaves of deciduous varieties are larger, softer in texture, rounded to oval and slightly toothed. Flowers of both types are generally showy, sometimes fragrant clusters or sprays of tiny flowers, ranging from creamy white to electrically–bright blue.
Culture: Grows in full sun to partial shade, with excellent drainage. Prefers lean soil conditions. Most are drought tolerant, to the point that they balk at summer water; winter wet will cause their demise, so rock gardens or containers that can be moved under cover suit them best. These plants can be “killed with kindness and too much water or fertilizer can result in a much shortened lifespan of this plant.
Pests & Diseases: Ceanothus can attract aphids, mealybugs and scale, though they’re not thought to be particularly prone to these pests. Fungal diseases can occur if given too much water in summer or if not properly drained. They have a reputation of being somewhat short-lived (< ten years), but it is thought that this is more due to poor placement when planting (over–rich soil, over–irrigating) rather than something intrinsic in the plant itself.