Caryopteris x clandonensis or Blue Mist Spirea is a very attractive shrub-like perennial plant that deserves to be used more often in our landscapes. It is not a member of the spirea family, although its foliage is somewhat reminiscent of a small spirea. Instead it is a herbaceous, woody perennial plant that develops into a small, woody shrub each summer then dies back to the ground in winter.

The leaves are long and narrow, usually with a smooth edge but some plants may have coarsely-toothed leaves. They are also a dark, bluish-gray green on the upper surface and grayish-white below. The flowers are produced in clusters in late summer and may be dark violet-blue or lavender-blue. The clusters of blue flowers are an attractive contrast to the many yellow daisy flowers that bloom in late summer. The mature height of the shrub is 3-4 feet. Full sun and well-drained soil are required for the best performance of this plant. Few insects or diseases are a problem for this plant, although some fungal leaf spots can be a problem if spring conditions are very wet and humid.

Several cultivars of Caryopteris x clandonensis are available including the following: 

• 'Azure' is a 3 foot tall plant with light blue flowers.

• 'Blue Mist' is a 3 foot tall plant with gray-green foliage and light blue flowers.

• 'Dark Knight' is a 3 foot tall plant with dark blue flowers.

• 'Heavenly Blue' has darker green leaves and deep blue flowers.

• 'Kew Blue' is a 2 foot tall plant with dull green leaves and dark blue flowers.

• 'Longwood Blue' is a 1 1/2-2 foot tall plant with silvery green leaves and sky blue flowers.

• 'Worcester Gold' is a 3 foot tall plant with yellow-gold foliage in spring and early summer. The flower are medium blue.