Santa Barbara ceanothus

Santa Barbara ceanothus: how do you recognise it?

Habit

A dense, spreading shrub about 1.5 m tall and up to 2.5 m wide, with arching branches.

Leaves

Small, oval to roundish, dark green and glossy, with deeply impressed veins and slightly rolled edges.

Flowers

Small, rounded clusters of tiny dark blue flowers, in April–May.

Roots

Deep and branching, with nodules of nitrogen-fixing bacteria; it does not transplant well.

Lifespan

Rather short-lived: after a number of years the shrub becomes woody and bare, and a young plant is then the best solution.

Flowering: April–May · Plants: April–May · Pruning: June

Why grow it?

• One of the most intensely blue-flowering shrubs: in April–May a single blue cloud.
• Bees flock to it in great numbers.
• Evergreen: a dense, dark green shrub even in winter.
• Drought-tolerant once established, ideal for a sunny, dry spot against a wall.
• Lovely as a free-standing shrub or loosely trained against a wall or fence.
• It fixes its own nitrogen through root nodules, so it needs no fertiliser.

Santa Barbara ceanothus: where does it grow best?

• Full sun, ideally in front of a south- or west-facing wall.
• Sandy or loamy, well-drained soil, acid to neutral; on chalky soil the leaves may turn yellow.
• Dry to normally moist; wet roots in winter are often fatal.
• Sheltered from cold east and north winds.
• Allow 2.5 m of width; plant 30–50 cm from a wall.

Light

Sun

Soil type

Sand or loam

Acidity

Acid or neutral

Moisture

Dry or normal

Size

1.5 m tall, 2.5 m wide

Hardiness

Hardy (to -15 °C)

Goes well with

• Lavender: Likes the same sunny, dry spot and flowers in summer, after the ceanothus.
• Rock rose: Also a lover of sun and drought, with white or pink flowers in May–June.
• Rosemary: Grey-green, aromatic leaves and pale blue flowers, for a Mediterranean corner.
• Broom: Yellow flowers in May, a classic contrast with the dark blue.
• Catmint: Blue summer flowers at the base, also drought-tolerant.

Santa Barbara ceanothus: when and how to plant it?

Plant in April–May.

1. Plant in April–May, when the soil has warmed up, so that it can root well before winter.
2. Dig a hole twice as wide as the root ball; if the soil is rather heavy, work in coarse sand or fine gravel.
3. Set the plant at the same depth as it was in its pot, 30–50 cm from a wall, disturbing the root ball as little as possible.
4. Water generously and keep the soil slightly moist in dry spells during the first year.
5. Against a wall, fix a few wires if you wish to tie in the main branches loosely.
6. Mulch with gravel or coarse bark rather than rich compost.

Care

Watering

Water in dry spells in the first year; after that, only during long, hot periods.

Feeding

Not needed: the plant fixes its own nitrogen. Too much fertiliser gives soft growth and fewer flowers.

Support

Against a wall, tie a few main branches loosely to wires; this also prevents wind damage.

Mulching

A layer of gravel or bark keeps the base dry and weed-free.

Moving

Avoid moving it: once established, it rarely settles well in a new spot.

Tip: Plant it against a sunny south- or west-facing wall in well-drained soil and, after flowering, trim only lightly, always within the leafy wood: it will stay dense and free-flowering for years.

Santa Barbara ceanothus: when to prune it?

Pruning months: June.

When: Prune lightly, straight after flowering in June. This evergreen species flowers in spring on last year’s wood.

How:

• Shorten the flowered shoots, but always stay within the green, leafy growth.
• Never cut into old, bare wood: it will not reshoot from it.
• Dead or frosted branches can be removed at any time, back to healthy wood.
• For a wall-trained shrub: after flowering, cut back outward-growing branches and tie in new shoots.

Caution: Never prune hard and never in autumn: hard or late pruning can kill the plant.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Semi-ripe cuttings

In July–August, take 8–10 cm cuttings, remove the lower leaves and root them in a mix of cutting compost and sand under plastic or in a cold frame. Overwinter frost-free and plant out in spring.

Layering

In spring, peg a low branch down into the soil and carefully sever it after a year.

Santa Barbara ceanothus: how does it get through the winter?

Hardy to −15 °C: protect young plants.

• Hardy to about −15 °C: in a sheltered, dry spot it survives most Belgian winters.
• In harsh winters the leaves may turn brown and branches may die back; cut these out once new growth begins.
• Protect young plants in severe frost with a double layer of horticultural fleece.
• In a pot: keep the pot dry and sheltered against a south-facing wall and wrap it; pots are more vulnerable than plants in open ground.

Diseases and pests

• Root rot: The plant wilts and suddenly dies, often after a wet winter. Prevent it with well-drained soil and a dry spot.
• Frost damage: Brown leaves and dead branches after hard frost. Wait until new growth starts, then cut back to healthy wood.
• Yellow leaves: On chalky soil. Choose acid to neutral soil or work leaf mould in around the plant.
• Scale insects: Small brown shells on the branches and sticky honeydew. Brush or rub them off; ladybirds help too.
• Bare, woody shrub: Normal after a number of years. Take cuttings in good time and replace the old plant.

Through the year

• January: In severe frost, cover young plants with fleece.
• March: Remove the fleece once the hardest frosts are over.
• April: Flowering begins. Plant.
• May: Full flower, busy with bees. Plant.
• June: After flowering, prune lightly, never into bare wood. Tie in new shoots.
• July: Take semi-ripe cuttings. Water young plants in dry spells.
• August: Take semi-ripe cuttings. Water during long droughts.
• September: No more pruning or feeding.
• November: Prepare young plants and pots for winter.

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Did you know?

• Ceanothus has root nodules containing bacteria that fix nitrogen from the air, just as members of the pea family do.
• Dozens of Ceanothus species grow in western North America, especially in California; in English they are known as California lilac.
• Impressus means ‘pressed in’ and refers to the deeply sunken veins of the leaf.