Caryopteris is a genus of flowering plants that had been placed in the Verbenaceae family, and has been more recently assigned to the mint family, or Labiaceae. Commonly known as bluebeard, this genus includes both herbaceous plants and shrubs that are native to Asia. The plants have blue flowers, bloom in late summer, and are somewhat drought-tolerant, which makes them highly desirable for flower borders. A number of cultivars have been developed and are widely grown.
The hybrid Caryopteris x clandonensis is the source of many of the cultivars that are grown as ornamental plants. This hybrid grows to 2-3 ft (0.6-0.9 m) tall and equally wide. It will grow in full sun or light shade, and in moist or dry soil. It is important that the soil have good drainage. Poor drainage is considered the most severe problem in growing Caryopteris.
The leaves of this plant are about 3 in (7.5 cm) long and narrow. The flowers are small and produced in profusion at the top of the stems. Their blue coloring and production in autumn makes them desirable for flower beds, since very few shrubs bloom at this time. It is recommended to prune back the dead wood, since flowers are produced on new wood.
Some of the popular cultivars for this hybrid include Blue Mist, which has silver green foliage contrasting with blue flowers. Dark Knight has purple flowers that are attractive to hummingbirds. Heavenly Blue is a smaller plant with dark blue flowers, while Worcester Gold has foliage that changes from yellow to yellowish-green as it ages.
Longwood Blue grows to 4 ft (1.2 m) tall and has flowers that are more violet in color than the other cultivars. In cooler climates, these plants will die back to the ground during the winter. First Choice is more compact than the other cultivars. It blooms earlier than the other types of Caryopteris, and has dark purple-blue flowers. It is also drought-resistant.
These shrubs should be planted in a hole that is twice the size of the root ball. The plant should also be placed at the same depth as in the original pot. In the spring, it should be pruned vigorously to generate new growth. It is also suggested to prune after each flowering cycle, so there will be more new growth and, subsequently, more flowers.
It is recommended to occasionally water the plants deeply. This encourages them to keep flowering. Propagation is done by terminal cuttings taken late in the spring or early in the summer.