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C. montana has a loose, rounded habit.

Involucral bracts add to the unusual mix of ray and disc flowers.

Asteraceae

Two-inch flowers are a loose bouquet of long ray petal flowers with shorter disc flowers in the center. The flowers are wrapped in round involucral bracts edged in black, which look somewhat like upside-down roof shingles. Leaves are alternate, lanceolate. Because only a few flowers bloom at one time, it is best to plant Centaurea in groups. However, because it is stoloniferous and likes to travel, gardeners must either give it lots of space or be willing to rip it out of the ground when it begins to encroach.

Plant Type: perennial

Plant Form or Habit: rounded/mounded

Plant Use: Planted in groups in beds and borders, as cut flowers

Propagation:

division

Flower Color:

light blue
dark blue
lavender

Bloom Period:

early summer
mid-summer
early fall

Width: Minimum: 12 inches     Maximum: 24 inches

Foliage Texture: medium

USDA Hardiness Zone: 4

Water Requirements: average

Additional Comments: Wild forms of Centaurea, or knapweed, may be found alongside country roads in the Northeast. An astringent herb, its flowers have been used as an ingredient for eye ailments such as conjunctivitis and corneal ulcers as well as for minor wounds and ulcers of the mouth. Flowers are edible. Extracts of the plant are used in shampoos and conditioners. Dry flowers for pot pourris. Centaurea is named for Chiron, a centaur known for his herb knowledge and who first introduced Centaurea as a healing plant.