Ceratostigma willmottianum

Ceratostigma willmottianum

Ceratostigma willmottianum is a deciduous shrub that provides great interest in early autumn when its slender stems bear pale blue flowers amongst the foliage that gradually turns red as the autumn season develops. This shrub is easy to grow in a sunny, well-drained spot and can be cut hard back in the spring where it can be utilised at the front of beds and borders in small or large gardens. At RHS Garden Hyde Hall this Ceratostigma is grown in bold clumps on Clover Hill, where it contrasts well with autumn-flowering grasses and is effective at hiding the bare bases of their stems. It can also be seen by the Dry Garden at Hyde Hall.

Vital statistics

Common name

Chinese plumbago

Family

Plumbaginaceae

Height & spread

50-100cm (1.6-3ft) tall by 100-150cm (3-5ft) wide

Form

Semi-woody perennial

Soil

Light soil

Aspect

Full sun

Hardiness

Hardy down to a range of -12°C to -18°C

Ceratostigma

The eight species of semi-woody, sun-loving Ceratostigma can be evergreen or deciduous shrubs or herbaceous perennials. They come from dry open places across Asia, plus tropical Africa. They have simple leaves which usually colour well in autumn, and short terminal or axillary spikes of salver-shaped blue flowers in late summer and autumn. There are three species which are commonly grown in gardens.

The name comes from the Greek word keras meaning horn in reference to the hornlike structure on the stigma of the flower. 

Ceratostigma willmottianum

C. willmottianum is a small deciduous bushy shrub from China and Tibet with rounded leaves, often edged with purple, that turn red in autumn. It bears light sky-blue flowers 2.5cm (1in) in width, from August to October in dense clusters. Although it’s a woody plant, it may die back to ground level in cold areas and reshoot in late spring. 

It is named after Miss Ellen Ann Willmott (1860-1934) who was a well-known English amateur gardener.

Cultivation

• Grows best in full sun but will tolerate partial shade.
• Generally free from pests but may suffer from powdery mildew.

Propagation

• Take semi-hardwood cuttings.
• Can also be propagated by division.

AGM

The RHS Herbaceous and Woody Plant Committees awarded Ceratostigma willmottianum an Award of Garden Merit in 1993 and described it as:

'Small deciduous shrub with lanceolate leaves to 5cm long, turning red in autumn. Flowers 2.5cm wide, rich blue, in dense terminal clusters.'