The botanical name for the Blue Mist shrub is Caryopteris x clandonensis (kar-ee-OP-ter-iss, klan-don-EN-sis) a mounded, fairly low-growing perennial deciduous shrub sporting scented foliage and clouds of delicate blue flowers in late summer.
The plants’ genus name is derived from the Greek word, karyon, which means “nut,” as well as the Greek word, pteron, which means “wing.”
This term refers to the winged fruit’s the shrub produces.
The common name for Caryopteris plants include:
- Dark Knight
- Blue Spirea
- Blue Mist
The Caryoptis is a member of the Lamiaceae family hailing from Mongolia, Japan, Korea, and China.
Blue Mist (clandonensis) is a cultivar of this genus.
Caryopteris Blue Mist Shrub Care
Size & Growth
Dark Knight can grow 18″ to 30″ inches in a single year.
The maximum height is 3′ feet tall. The plant has a spread of 2′ to 3′ feet wide.
The oval leaves appear slowly in the springtime.
Don’t worry if your Bluebeard stays bare for a while early in the spring. This is no cause for alarm.
When the leaves do emerge, they will be oval or elliptic.
They are grayish/green and slightly toothed with fuzzy undersides.
When you brush them with your hand, they emit a pleasant fragrance.
Flowering & Fragrance
Blue Spirea flowers grow in cloud-like clusters from July through late September.
The showy, powdery blue blooms are very fragrant and extremely attractive to beneficial insects such as bees, butterflies, and other pollinators.
Light & Temperature
Blue Mist should be planted in full sun.
It is winter hardy in USDA hardiness zones 5-8, but the top growth may suffer a bit in winter below zone 7.
If you do live in one of the cooler zones within the plants’ range, expect the stems to die back to the ground in the wintertime.
New growth will appear in the spring.
Watering & Feeding
Dark Knight should be kept fairly well-watered during the first year.
Once established, these plants are drought tolerant and do not usually need additional watering.
Blue Caryopteris clandonensis needs very little in the way of fertilizer.
It is better to feed these shrubs with a side dressing of good compost than to provide fertilizer.
Excessive fertilizer stimulates leaf growth and diminishes bloom production.
Soil & Transplanting
Blue Spirea likes a loose, loamy, well-drained soil with a neutral pH level.
Incorporate plenty of light organic matter into the soil to promote the correct level of water retention and drainage.
Take care to place your young Caryopteris in the planting hole level with the soil surface or just slightly higher.
Grooming & Maintenance
In USDA hardiness zones 5 and 6, you may wish to cut back your Bluebeard back to the ground at the end of the growing season.
This will prevent damage caused by winter cold and promotes vigorous growth in the springtime.
Hard pruning late in autumn is a good plan in zones 7 and 8, as well.
This type of winter management will not harm flower production and allows you to get a fresh start with your Bluebeard every spring.
How To Propagate Caryopteris
Blue Mist grows from seed, and it may self-sow in ideal conditions.
It is also possible to propagate the plant using soft-wood cuttings late in the springtime.
Blue Mist Shrub Pest or Disease Problems
Dark Knight is not typically bothered by pests when well cared for.
Compromised plants may be troubled by 4-Line Plant Bugs during June.
This does cause unsightly mottling of the leaves, but it doesn’t cause significant damage to the plant overall.
These bugs are short-lived and will be gone before you need to do anything about them.
If overcrowded or kept in poorly draining soil, Blue Mist Shrub can suffer from crown rot.
Is The Blue Mist Toxic Or Poisonous?
Blue Mist Shrub has not been reported as having any toxic effects.
Is The Caryopteris Invasive?
Although this plant does not appear to be listed as invasive, the seeds are easily spread by wind, running water, birds, and animals.
The Australian government is keeping a close eye on it for invasive potential.
Suggested Caryopteris Blue Mist Shrub Uses
With its good looks and pleasant scents, Blue Spirea is a nice choice in mass plantings or as a border or container plant.
It is an excellent addition to your bee and pollinator garden.
The soft, blue flowers are fine sources of nectar and pollen for beneficial insects in late summer.