Centaurea Species, Black Knapweed, Hardheads, Lesser Knapweed, Spanish Buttons

Centaurea nigra

Family: Asteraceae (ass-ter-AY-see-ee) (Info)
Genus: Centaurea (sen-TAR-ee-uh) (Info)
Species: nigra (NY-gruh) (Info)

Category:

Perennials

Water Requirements:

Drought-tolerant; suitable for xeriscaping

Average Water Needs; Water regularly; do not overwater

Sun Exposure:

Full Sun

Foliage:

Herbaceous

Foliage Color:

Blue-Green

Orange/Apricot

Height:

12-18 in. (30-45 cm)

18-24 in. (45-60 cm)

24-36 in. (60-90 cm)

Spacing:

3-6 in. (7-15 cm)

6-9 in. (15-22 cm)

9-12 in. (22-30 cm)

12-15 in. (30-38 cm)

15-18 in. (38-45 cm)

18-24 in. (45-60 cm)

24-36 in. (60-90 cm)

36-48 in. (90-120 cm)

4-6 ft. (1.2-1.8 m)

6-8 ft. (1.8-2.4 m)

8-10 ft. (2.4-3 m)

10-12 ft. (3-3.6 m)

12-15 ft. (3.6-4.7 m)

15-20 ft. (4.7-6 m)

20-30 ft. (6-9 m)

30-40 ft. (9-12 m)

over 40 ft. (12 m)

Hardiness:

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)

USDA Zone 9b: to -3.8 C (25 F)

USDA Zone 10a: to -1.1 C (30 F)

Where to Grow:

Grow outdoors year-round in hardiness zone

Can be grown as an annual

Danger:

Unknown - Tell us

Bloom Color:

Pink

Bloom Characteristics:

This plant is attractive to bees, butterflies and/or birds

Bloom Size:

Unknown - Tell us

Bloom Time:

Mid Summer

Late Summer/Early Fall

Other details:

May be a noxious weed or invasive

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:

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

Seed Collecting:

Bag seedheads to capture ripening seed

Collect seedhead/pod when flowers fade; allow to dry

Allow pods to dry on plant; break open to collect seeds

Allow seedheads to dry on plants; remove and collect seeds

Unblemished fruit must be significantly overripe before harvesting seed; clean and dry seeds

Properly cleaned, seed can be successfully stored

Regional

This plant is said to grow outdoors in the following regions:

Washington, Maine

Roswell, New Mexico

Knoxville, Tennessee

Gardeners' Notes:

0
positives
1
neutral
0
negatives
RatingContent
Neutral

On Aug 7, 2006, charlotte35 from Washington, ME (Zone 4a) wrote:

This plant "volunteered" in my yard last summer (2005). It's come up again this year in the same place. It's been identified differently by several of my friends/observers. Its spread is about 5 feet. It's fragrant and the bees of all kinds love it. I'd love to know all about it.

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