Blue Beard (Blue Mist) Plant Profile

A Favorite of Bees and Butterflies

blue mist shrub

The Spruce / Evgeniya Vlasova

Whether you know it as blue beard or blue mist, Caryopteris x clandonensis is one of the few plants that produce genuinely blue flowers. This plant originated as an accidental hybrid of C. incana and C. mongholica and has since been bred to produce several popular cultivars. The compact size and soft gray foliage make blue beard plants a good choice in any size garden.

Depending on the climate, these plants are grown either as deciduous shrubs or woody perennials that die back to the ground each winter. Growing from neat low mounds, the narrow silvery-gray leaves resemble those of willow. Ideally, the plant should be planted in the spring or fall, provided that your area doesn't get too cold. Clandonensis hybrids typically grow between 18 and 30 inches annually.

Fun Fact

The plant's common names come from the hue of the flowers. The blue or purplish blooms, appearing are mid-to-late summer, are clustered in panicles above the foliage in small feathery puffs.

Botanical Name Caryopteris × clandonensis
Common Names Blue beard, blue mist 
Plant Type Deciduous shrub or woody perennial
Mature Size 2 to 4 feet tall with a similar spread
Sun Exposure Full sun
Soil Type Medium moisture, well-drained soil
Soil pH 6.5 to 7.5 (slightly acidic to slightly alkaline)
Bloom Time Mid-to-late summer
Flower Color Blue, purple; pink cultivars available
Hardiness Zones 5 to 9 (USDA)
Native Area Parent species are native to East Asia
closeup of blue mist shrub

The Spruce / Evgeniya Vlasova

blue mist shrub

The Spruce / Evgeniya Vlasova

blue mist shrub detail

The Spruce / Evgeniya Vlasova

Blue Beard Care

The compact size and soft gray foliage make blue beard plants a good choice in any size garden. This is a versatile plant, equally at home in perennial borders, shrub borders, or as a small hedge plant. It is very effective planted in mass and is highly valued for its late summer flowers when few other shrubs are blooming.

Blue beard plants are low-maintenance—they tolerate both drought and shade, and they don't need much fertilizer, if any. However, like all other plants, blue beards have their preferences, so you should plant them in full sun and with medium-moisture soil if you want them to thrive.

Light

Caryopteris plants should be sited in full sun for best blooms. They will tolerate some shade, although flowering will be somewhat reduced. Blue beard may bloom later in the season when they are planted in a shady location.

Soil

Caryopteris prefers a medium-moisture, well-draining soil, though it tolerates fairly moist soil. It does not tolerate wet, poorly drained soils. They thrive best with a neutral soil pH, but will accept slightly acidic or slightly alkaline conditions.

Water

Blue bears are drought-tolerant, but water the plants regularly when young. Once established, they don’t require any supplemental watering unless you are having a particularly dry season.

Temperature and Humidity

Blue beard is reliably hardy in USDA zones 5 to 9; however, in the northern part of the range (zones 5 and 6), it may die back to ground level in winter. This is not a problem, though, because this is a fast-growing shrub that blooms on new growth from the current year.

Fertilizer

These plants are not heavy feeders, so some organic matter mixed into the planting hole should be all the food they need. Side dressing with compost is preferred over fertilizing Caryopteris plants. Too much fertilizer makes for a leafy plant with fewer blooms.

Varieties of Blue Beard

  • Caryopteris x clandonensis : The original hybrid is one of the hardiest forms available and still one of the most popular.
  • 'Dark Knight': This variety has the darkest blue flowers, but it is a bit more temperamental to grow.
  • 'Sunshine Blue': This cultivar has deep blue flowers offset by yellow foliage.
  • ‘Pink Chablis’: This Proven Winners introduction has pink flowers.
  • ‘Longwood Blue’: This variety has sky-blue fragrant blooms and has a taller stature that's about 4 feet high.
  • ‘Worchester Gold’: This cultivar has golden foliage and lavender flowers.

Pruning

To keep the plant shaped and flowering, Caryopteris plants should be cut down by at least half in the early spring. You can cut them back to 12 to 18 inches without harm. As the plants age, you will get some dead wood in the center. Prune this out as needed. If the plants die back in winter, remove the dead stalks in spring as new growth is beginning.

Tip

Blue beard is slow to leaf out in the spring, so don’t panic if yours looks like a dead twig. Be patient.

Propagating Blue Beard Plants

Blue beard may self seed, and the volunteers can be transplanted as you wish. You can also propagate by soft-wood cuttings in late spring. Cut 6-inch segments off new-growth stems, then remove the lower pairs of leaves. Dip the ends of the cuttings in rooting hormone, then plant them in potting mix. Keep the cuttings in bright indirect light and make sure they are well-watered until they have developed good root systems.

Common Pests/Diseases

Caryopteris can be bothered by the four-line plant bug in June. The foliage will get mottled, but it doesn’t harm the plant and the bug moves on quickly enough. If the bugs disturb you, insecticidal soap, horticultural oil, or neem oil will control them.