Chinese Plumbago has vivid cobalt-blue flowers

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Cerastostigma willmottianumCerastostigma willmottianumChinese Plumbago is loved for its masses of vivid cobalt-blue flowers from late summer through autumn.

This delightful little plant is native to East Asia, occurring from Western China to Tibet. In the wild it can be found growing in warm valleys and at forest edges, or in thickets. It is named after Miss Ellen Ann Willmott, a celebrated English gardener, and is loved for its masses of vivid cobalt-blue flowers which appear from late summer and continue through autumn, when many other flowers have gone over. Flowering lasts for six weeks or more and is a very welcome sight.

(Ceratostigma willmottianum) belongs to the Plumbago family (Plumbaginaceae) and is often called “Hardy Plumbago.” The flowers have the same wheel-like form as plumbago, and will attract butterflies and hawk moths to your garden. In late summer the small leaves start turning bronze and by mid-autumn they will be a bright russet-red. Botanists and gardeners alike seem to be unsure whether to classify Ceratostigma willmottianum as a shrub, a sub-shrub, or herbaceous perennial because during some winters the plant will die back right down to the ground; while during other winters the top growth will remain all winter. It grows quickly to +-90cm to 1m tall, spreading wider than its height, to +-1.5m. Its smaller cousin (Ceratostigma plumbaginoides) has flowers that are just as blue, but it reaches no higher than 30cm and is completely herbaceous.

In the Garden:

The Chinese forget-me-not is a low-growing, spreading plant which looks beautiful planted in front of larger shrubs, or in the mixed perennial flower border. Its low spreading habit looks great in pebble and rock gardens, or even as a ground cover in tough, dry and sunny spots in the garden. It is also excellent to stabilise the soil on banks and slopes; and pots overflowing with their vivid blue flowers and flame-coloured leaves look gorgeous in terracotta pots placed on steps, or planted at the corners of beds, or perhaps along a pathway.


Chinese plumbago will grow throughout the country, except for very hot and humid regions. It loses its leaves or goes totally dormant in winter and is hardy to frost and temperatures as low as -15°C. It thrives in full sun but will take partial shade, especially in very hot regions. This plant prefers light (sandy) and medium (loamy) soils that drain well, and can be planted in nutritionally poor soil. It will grow in acid, neutral and basic (alkaline) soils, and even in very alkaline soils. It is well suited to drier soils such as chalk and resents soggy, wet conditions, but will grow in clay soil which drains well, as long as the beds are well-prepared with grit or gravel incorporated into them. Do not use peat or rich organic material such as animal dung in the planting hole - a little compost and a dressing of bone meal will suffice.

It is best to prune back hard in spring because the plant flowers best on the current year's growth. After pruning, apply a generous mulch of well-rotted garden compost around the base of the plant. Once established the Chinese forget-me-not is hardy to drought but will respond well to moderate watering during dry summer spells.

Propagate from softwood cuttings taken in spring, or by layering or division of the root ball. Plants often self-layer in the garden.

Pests & Diseases:

Generally Ceratostigma is pest free but may suffer from powdery mildews.


It is reported not to be non-toxic to dogs, cats, and horses. In humans with sensitive skin it may cause skin irritation or allergic reaction; so it is advisable to wear gloves when pruning the plant.