Ceanothus

How to grow ceanothus

Find out all you need to know about growing ceanothus, in this practical Grow Guide.

A table displaying which months are best to sow, plant and harvest.
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Plant
Plant

Do not Plant in January

Do not Plant in February

Do not Plant in March

Do not Plant in April

Do not Plant in May

Do not Plant in June

Do not Plant in July

Do not Plant in August

Do Plant in September

Do Plant in October

Do not Plant in November

Do not Plant in December

Flowers
Flowers

Plant does not flower in January

Plant does not flower in February

Plant does not flower in March

Plant does not flower in April

Plant does flower in May

Plant does flower in June

Plant does not flower in July

Plant does not flower in August

Plant does not flower in September

Plant does not flower in October

Plant does not flower in November

Plant does not flower in December

Cut back
Cut back

Do not Cut back in January

Do not Cut back in February

Do not Cut back in March

Do not Cut back in April

Do not Cut back in May

Do not Cut back in June

Do Cut back in July

Do Cut back in August

Do not Cut back in September

Do not Cut back in October

Do not Cut back in November

Do not Cut back in December

A ceanothus in flower, is a sure sign that summer has arrived. The blue flowers appear in joyful abundance in May and June, on otherwise fairly humble shrubs. These azure clouds give a candy coating not dissimilar to the sprinkles on blue liquorice allsorts. Also known as California lilacs, which tells us their country of origin, these sun-loving shrubs come in a range of sizes to suit most gardens. The evergreen varieties tend to be slightly less hardy, but can be grown as free-standing shrubs or small trees in sheltered gardens. The prostrate forms work well as ground cover. Pollinating insects love the blue flowers as much as we do.

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Take a look at our start-to-finish guide to growing ceanothus, below.


Planting position

Take into account the Californian origins of Ceanothus and choose a spot in full sun. Soil should be moist but well-drained. In more exposed gardens, Ceanothus will benefit from being planted near a south- or west-facing wall that will give some shelter from cold winds and winter frost. If you can’t provide shelter, choose one of the hardier, deciduous varieties.


Planting ceanothus

Plant ceanothus in the autumn when the soil is still warm. Dig a generous hole and add handfuls of grit so the soil is very well drained.

How to plant ceanothus


Propagating ceanothus

The accepted method for the evergreen varieties is to take semi-ripe cuttings from the current season’s growth, after flowering, any time up until the autumn. For deciduous varieties, take softwood cuttings from new growth in spring.


Ceanothus: problem solving

Ceanothus is a relatively pest and disease free shrub and should thrive, provided the planting conditions are right. It is on the list of shrubs that can succumb to honey fungus, and in some case, it can be prone to scale insects.


Looking after ceanothus

Trim annually to keep plants bushy and leafy. Cut dead wood in the spring and trim side-shoots after flowering. If you inherit a Ceanothus that has outgrown its position or become slightly unshapely, don’t try to prune it back hard as they don’t recover successfully.


Ceanothus varieties to try

Ceanothus thyrsiflorus var repens
Ceanothus thyrsiflorus var repens
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  • Ceanothus ‘Concha’  – an evergreen cultivar with arching branches and a dense growth habit, flowering in April and May. The Royal Horticultural Society has given it the prestigious Award of Garden Merit (AGM).
  • Ceanothus ‘Cynthia Postan’  – hardy and evergreen, this is perfect for growing in a mixed border. It can be also be trained against a wall or fence or grown as a small standard shrub.
  • Ceanothus thyrsiflorus var. repens  – one of the hardiest varieties, this is a low-growing evergreen, forming a natural mounded shape. It looks good at the front of a mixed border. It holds the RHS AGM.
  • Ceanothus ‘Blue Cushion’  – a compact, evergreen variety with small, oblong, dark green leaves. The flowers are a darker blue than other varieties, and appear in late spring. In very cold winters, plants may need some protection from frost.
  • Ceanothus ‘Autumnal Blue’ – a taller, late flowering variety, growing to 3m in height. Another variety with the RHS AGM.
  • Ceanothus ‘Gloire de Versailles’ – a medium sized, deciduous variety, that can tolerate a more exposed planting position. RHS AGM.