Centaurea cyanus
An annual in the Asteraceae native to Europe and Western Asia that readily naturalizes in North America, bears blue flower heads 1.5–3 cm in diameter with a ring of spreading ray florets around a central cluster of disc florets, and is valued as a bedding plant and cut flower for its brilliant blue blossoms that attract butterflies.
Common Names
Cornflower, Bachelor's Button, Bluebottle, Ragged Sailor, Ragged Robin, Bluebonnet, Bluets
Summary
Centaurea cyanus, commonly known as cornflower or bachelor’s button, is an annual flowering plant native to Europe. It grows to about 0.5–1 m tall with lance-shaped leaves and solitary deep blue flowerheads 3–4 cm across, often with violet-blue inner florets, and blooms from late spring through July; cultivars also come in pink, white, or red and blooms attract bees and other pollinators.
Propagation is by seed sown directly in spring or indoors, with self-seeding common. Prefers full sun and well-drained soil, tolerating a range of soils from poor to rich; taller forms may require staking, deadheading prolongs bloom, and plants suit beds, borders, cottage gardens, wildflower meadows, and containers.
Lifecycle
Annual
Height
12-36 inches
Spread
12-24 inches
Hardiness Zones
Zones 2-11
Sunlight Requirements
Ideally Full Sun; tolerates Partial Sun and Partial Shade.
Soil Type
Well-drained soil
Soil Drainage
Well-drained soil (moist but not waterlogged).
Soil pH
Broad pH tolerance; no single ideal pH, tolerates acidic to alkaline soils.
Bloom Color
Blue
Bloom Time
Spring and Summer
Foliage Color
Green
Fall Foliage Color
Green
Leaf Lifecycle
Deciduous
Growth Rate
Fast
Seasons of Interest
Spring and Summer
Propagation Methods
Seeds
Attracts Wildlife
Attracts bees, butterflies, other pollinators, and birds
Taxonomy
- Taxonomic Rank
- Species
- Author
- L.
- Publication
- Sp. Pl. : 911 (1753)
Superior Taxa
- Kingdom
- Plantae
- Subkingdom
- Pteridobiotina
- Phylum
- Angiosperms
- Order
- Asterales
- Family
- Asteraceae
- Subfamily
- Carduoideae
- Tribe
- Cardueae
- Subtribe
- Centaureinae
- Genus
- Centaurea
Synonyms
Cyanus vulgaris Centaurea pulcherrima Cyanus dentato-folius Centaurea cyanus var. cyanus Jacea segetum Cyanus segetum Centaurea umbrosa Leucacantha cyanus Centaurea cyaneum Centaurea cyanus var. denudata Centaurea cyanus subsp. coa Centaurea rhizocephala Cyanus cyanus Centaurea concinna Centaurea lanata Centaurea cyanus subsp. cyanus Centaurea cyanocephala Centaurea segetalis Centaurea concinna Cyanus arvensis Centaurea pulchra