Scientific:
Centaurea cyanus (Synonym: Centaurea concinna, Centaurea cyaneum, Centaurea pulchra, Cyanus cyanus, Cyanus vulgaris, Leucacantha cyanus)
Common: bachelor buttons, blue bachelor buttons, corn flower, garden cornflower, basket flowers, blue bonnets, blue cap
Family: Asteraceae
Origin: South England, Whales, northwestern Europe and the Mediterranean region of southern Europe where native populations are diminishing, but in contrast it has naturalized across nearly all of the continental United States and Canada.
Pronounciation: Cen-TUR-e-a sigh-AN-us
Hardiness zones
Sunset All (warm or cool season annual depending on zone)
USDA All (warm or cool season annual depending on zone)
Landscape Use: Accent plant for flower borders, cut flowers, winter annual habitat gardens.
Form & Character: Upright, open, cool, informal, carefree, free spirited.
Growth Habit: Rapidly growing herbaceous annual branching to 2- to 3-feet tall.
Foliage/Texture: Leaves are covered with small white hairs causing the plant to have a glacous silver, grey or blue-gray appearance, older leaves are lyrate-pinntified or narrowly oblanceolate, entire or broadly serrate, young leaves a linear to linear lanceolate, highly pubescent, sessile; medium texture.
Flowers & Fruits: Ray flowers to 1 inch in diameter, intense sapphire, pale blue, or deep blue color (rarely pink), arranged in flowerheads called "capitula" with a ring of several large, spreading ray florets surrounding a central cluster of disc florets; fruits are elongated pappus bristles, somewhat blackened and cone shaped.
Seasonal Color: Bachelor buttons bloom heavily during the cool season in Phoenix. Many flower colors are available such as pink, light blue, medium blue,
blue-violet, white, and off white.
Temperature: Cold tolerant, but avoid high heat of western exposures to extend viability throughout spring months.
Light: Full sun to partial shade.
Soil: Tolerant, but in Phoenix does best in an organic matter amended soil that is well drained.
Watering: Regular supplemental water is necessary in Phoenix.
Pruning: Remove spent flowers, otherwise none.
Propagation: Seed, fresh seed germinate quickly in 7 to 25 days at 60o to 70oF with no additional treatment.
Disease and Pests: None
Additional comments: Bachelor buttons grows quickly and blooms heavily. This is a surprisingly easy plant to culture in flower borders in Phoenix as a fall, winter or spring annual. It's not for summer though (it's way too hot in Phoenix). Overall, bachelor buttons is an outstanding performer for mixed flower borders whether your preference is for cutting or admiring. It is attractive to bees, butterflies and/or birds. Sadly, it is not as commonly seen today in Phoenix landscape gardens as it used to be back in Grandma's day.
There are many named cultivars including:
Miscellaneous factoids: The nickname "cornflower" comes from the fact that the plant grows wild in the grain fields of southern Europe. It has naturalized throughout much of North America. The blue flower pigment is protocyanin, which in roses is red. The flowers are used traditionally in European phytotherapy to treat eye inflammations and contain polysaccharides (galacturonic acid, arabinose, glucose, rhamnose, and galactose) with anti-inflammatory properties. The edible flowers can be used in salads as a touch of added color. Petals are often dried and added to loose tea blends to enhance color. Flowers pigments are a bio-source for painting or dyeing fabric.
