Ceanothus – The Blues And Royal


Ceanothus is identical to blue, And Blue is an extraordinary color in the garden.

Whereas a mixture of reds, oranges, and even purple fight it out with élan, and pinks and mauves bed down sympathetically together; varying shades of blue seem to strike a discordant tone.  True blue, the color of the sky in August or shadows in the snow, is rare in plants. Most ‘blues’ in the plant world tend towards mauve. And just the merest hint of green sends the color up a blind alley. Nothing seems to blend with it except perhaps lime-green and yellow. So perhaps ceanothus owes their popularity to the rarity of their distinctive color.

Species Hail From California

And Most of the best garden forms, hence its popular name, ‘Californian Lilac’. But a lilac it is not. As a West Coast native, it shares its love of sun, sea, and sand with other Californians. Cold, wet British summers are not to its taste. But in a draining soil in sun it makes an easy, fast-growing shrub that explodes with flowers in May and June. However, and in the plant world there’s always ‘however’, ceanothus are fairly short-lived and susceptible not just to summer wet, but to wind and extremes of winter frost. Consequently, they are often grown against the west or south-facing walls where the microclimate affords them their California dreams.

Ceanothus ‘Trewithen Blue’ makes a tall, large-leaved evergreen to about 7m (20-25ft) if left to its own devices. Its powdery blue flowers are borne in large clusters very prolifically in late spring and are constantly popular with bees and early butterflies. Smaller-leaved varieties are tougher and could be grown as free-standing shrubs somewhere sunny and sheltered from the wind. 


Ceanothus ‘Concha’ makes a magnificent specimen that reaches about 3m (9-10ft) in all directions. Its flowers are a rich dark blue, the color of new jeans, and smother the plant in May and June. Thereafter C. ‘Concha’ has room to let. It could accommodate a later flowering Clematis viticella, such as C. ‘Prince Charles’. The clematis should be cut down to about 30-45cm (12-18ins) from the ground in early spring, then its pale blue flowers will appear in July and August to give its host a grand finale.

Some ceanothus requires no tenants. They produce another flush of flowers in late summer and autumn. Although the flowers are a little less dense and prolific, their hazy blues offset the golden October colors like wood-smoke from a smoldering fire. Ceanothus ‘A.T. Johnson’ has an especially long flowering season that peaks in spring and again in the autumn.

It carries smaller blue flowers over evergreen foliage. And C. Autumnal Blue’ is one of the hardiest evergreen varieties reaching to about 1.5m (5-6ft). Ceanothus ‘Gloire de Versailles’ is an old hybrid that has stood the test of time. Against a warm house wall where it can reach its 4-4.5m (12-15ft) potential, its loose, lacy, rose-blue flowers will attract every passing bee and butterfly from miles around until the first frosts drop both the flowers and the leaves.

Pink and white-flowered ceanothus may seem to some heretical, an aberration, but they are equally pretty, just not-blue: an exception that proves the rule. Ceanothus ‘Perle Rose’ is an old favorite with bright rose-carmine flowers in summer. And C. thyrsiflorus ‘Snow Flurry’ has small, dark evergreen leaves that show off the white flowers well.

No ceanothus needs a supporting cast to share the adulation, but a drift of Allium ‘Purple Sensation’ would exaggerate the deep blue intensity of, say, C. ‘Puget Blue’. Combine these with the lime-green and pink new foliage of Thalictrum flavum ‘Illuminator’ and you will have created quite a drama.

Then you could shock your friends to the core with an underplanting of cobalt blue Ceratostigma plumbaginoides beneath C. ‘Autumnal Blue’. It’s worth practicing the name.

They are sure to want to know the participants in this battle of the blues and royals.

The Ceanothus calendar

Mid March to late April– Feed your Ceanothus. Scatter a couple of handfuls of bonemeal around (but not touching) the base of the plant and cover with a mulch of compost.

Mid April. Prune summer and autumn flowering ceanothus

Early June. Prune spring flowering ceanothus after they have flowered.

Mid-August. Take cuttings from this year’s growth. Select a shoot where the tip is soft new growth, but the lower part is harder older growth. Take a cutting 6-8in long. Cut off the soft new growth at the top of the shoot just above a leaf joint. The ideal cutting should be about 2-4in long.  Dip the cutting in hormone rooting powder, put into compost and water well

Mid-October. Plant your new Ceanothus. Container grown examples can be planted at any time but the soil warmth and moisture gives the best start.

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