Caryopteris

Do you like the color blue in the garden? Blue Mist, Bluebeard, Blue Spirea, or Caryopteris, whatever you want to call it, this delightful late summer bloomer is a magnet for butterflies and a big asset in the late summer border.  Caryopteris has true blue flowers and is hardy, tough and easy to grow.

Caryopteris makes a nice low shrub for bordering walks and is excellent in larger mixed borders for late summer color.  It is a good plant for butterfly gardens, especially mixed with pink buddleia and goldenrod.  It can also be used as airy blue filler in floral arrangements

Caryopteris is a sub- shrub - it can die back to the ground each winter like an herbaceous plant or in warmer climates it can grow as a woody shrub.   Caryopteris leaves are generally silvery green, although variegated and golden leaved varieties exist.  The leaves are small and narrow, reminding one of willow leaves. In some varieties they are serrated at the edges, on others the edges are smooth and the leaf may be slightly lobed.

Caryopteris flowers are generally blue, although pink forms exist.  The flowers are carried on whorled spikes at the end of stems.  The long stamens stick out of each flower and the petals of the flowers have tiny extensions, which give the flower clusters a feathery appearance.  Butterflies and bees are very attracted to Caryopteris flowers.  The flowers are said to have a slight scent.

Caryopteris culture

Although it will sometimes re-seed itself in the garden, seed for Caryopteris is seldom offered to gardeners.  Caryopteris is generally purchased as a plant.  Try to buy a named variety rather than one just labeled Caryopteris or Blue Mist Shrub, as named varieties usually have better shape and more flowers.  Size of mature Caryopteris plants is about 3 foot by 3 foot.

Caryopteris is one of the few shrubs that will bloom in light or part shade.  They also do well in full sun.  They are hardy from zone 9 to at least zone 5.  In zone 5 Caryopteris may die back to the ground but will make substantial growth and will bloom by late summer.  Caryopteris blooms on new wood, so all winter-damaged wood can be safely pruned off in early spring without losing the flowers.  In fact, Caryopteris often has a better shape and looks fuller if it is cut back to about half its size each spring, regardless of winter damage.  Be a little patient with them in the spring as they are often slow to leaf out.

Caryopteris should be watered regularly but don’t fertilize unless your soil is quite poor.  Too much fertilizer makes more leafy growth than flowers.  They begin blooming in late summer and continue blooming until a hard frost.  Keeping the dead flowers trimmed off of Caryopteris prolongs the bloom.

Choosing Varieties

The Caryopteris in our gardens are hybrids of several Asian species.  They are generally referred to as Caryopteris x clandenensis although there are some other species on the market. ‘Longwood Blue’ is one of the best sky blue flowered varieties.  It also has nice silvery gray foliage.  ‘First Choice’ is a deep blue with a dense, compact growth habit.  ‘Sunshine Blue’ has golden leaves and deep blue flowers.   It is a good choice for warmer zones. ‘Summer Sorbet’ has green leaves edged in gold and deep blue flowers.  ‘Pink Chablis’ is a Caryopteris with pink flowers. Caryopteris divaricata, ‘Snowflake’ is a species of Caryopteris from the Himalayan Mountains.   It is a compact shrub, with slightly fuzzy green leaves edged in white.  The flowers are blue, but shaped a bit differently from other Caryopteris.  The leaves of this plant have an unpleasant smell.