Cornflower, Knapweed
Centaurea simplicicaulis

Family: Asteraceae (ass-ter-AY-see-ee) (Info)
Genus: Centaurea (sen-TAR-ee-uh) (Info)
Species: simplicicaulis (sim-plik-ee-KAW-liss) (Info)

Category:

Perennials

Foliage Color:

Silver/Gray

Bloom Characteristics:

Unknown - Tell us

Water Requirements:

Average Water Needs; Water regularly; do not overwater

Where to Grow:

Unknown - Tell us

Height:

6-12 in. (15-30 cm)

Spacing:

6-9 in. (15-22 cm)

Hardiness:

USDA Zone 4b: to -31.6 C (-25 F)

USDA Zone 5a: to -28.8 C (-20 F)

USDA Zone 5b: to -26.1 C (-15 F)

USDA Zone 6a: to -23.3 C (-10 F)

USDA Zone 6b: to -20.5 C (-5 F)

USDA Zone 7a: to -17.7 C (0 F)

USDA Zone 7b: to -14.9 C (5 F)

USDA Zone 8a: to -12.2 C (10 F)

USDA Zone 8b: to -9.4 C (15 F)

USDA Zone 9a: to -6.6 C (20 F)

Sun Exposure:

Full Sun

Danger:

Unknown - Tell us

Bloom Color:

Violet/Lavender

Bloom Time:

Mid Summer

Foliage:

Herbaceous

Other details:

Unknown - Tell us

Soil pH requirements:

6.1 to 6.5 (mildly acidic)

6.6 to 7.5 (neutral)

7.6 to 7.8 (mildly alkaline)

Patent Information:

Non-patented

Propagation Methods:

By dividing the rootball

From seed; direct sow outdoors in fall

From seed; winter sow in vented containers, coldframe or unheated greenhouse

From seed; sow indoors before last frost

From seed; direct sow after last frost

Self-sows freely; deadhead if you do not want volunteer seedlings next season

Seed Collecting:

Allow seedheads to dry on plants; remove and collect seeds

Regional

This plant has been said to grow in the following regions:

Brea, California

Columbus, Ohio

Stanwood, Washington

Gardeners' Notes:

1
positive
0
neutrals
0
negatives
RatingContent
Positive

On Oct 19, 2009, bonehead from Cedarhome, WA (Zone 8b) wrote:

Clear pink thistle like flowers in July. I have this tucked between a daylilly and earlier cornflower, for a nice combo. After bloom, I cut the whole plant back hard, and it often reblooms. It does occasionally get powdery mildew.