Ceratostigma is a genus of flowering subshrubs native to Asia. Several species are cultivated by gardeners in other regions of the world as ornamental plants. Nurseries may carry Ceratostigma species and can order them by special request. Gardeners can also cultivate the plants from divisions or cuttings, or order them directly through mail order plant services. Such services often provide access to rare cultivars that a nursery may not be able to get.
One popular Ceratostigma species for ornamental cultivation is C. plumbaginoides or blue plumbago, also known as blue leadwort. The physical characteristics of this plant are similar to most other species in the genus. It grows low to the ground as a groundcover or subshrub, and can spread rapidly in areas where the soil and light conditions are right and the plant is encouraged with fertilizer. This plant is used as a groundcover in many gardens and can also be used for borders and edging.
Members of this genus produce green foliage that will darken to red after the first frost and eventually drop off. In some regions where winter frosts do not occur, Ceratostigma can be cultivated as an evergreen. The flowers are blue to rich purple and have five petals. Flowering can occur throughout the summer and fall in healthy plants, and the flowers will remain while the leaves change color, creating a striking visual.
Hardy to zone five, these herbaceous plants prefer full sun to part shade. They can tolerate a variety of soil conditions, as long as the soil is not heavy and wet. In gardens with dense soil, sand can be worked into the soil to loosen it and improve drainage. While plumbago can be drought tolerant, it is advisable to keep the soil moist to support healthy plant growth. When the leaves die back, people can clip or mow back some of the branches to control the plant's growth and keep the garden looking neater. In the spring, new leaves and branches will appear.
In addition to being suitable for the garden, Ceratostigma can also be grown in containers. Container gardeners should use a moist, well-drained potting mix to avoid exposing the leaves to the risk of fungal infection and rot. People growing bulbs in containers might want to consider pairing the bulbs with a member of this genus. When the bulbs sprout, the foliage will be bare, and as the bulbs die off, the plant will leaf out, filling the container with greenery and color.