Bachelor’s Button

Bachelor’s Button

Centaurea cyanus

Status in Squamish:


Status in Whistler:


Status in Pemberton:

Vectors of Spread:

Cornflower, Garden Cornflower

ID Characteristics

General: Annual flowering plant in the daisy family (Asteraceae).

Flowers: Are pompom-like, with bracts at the base and fringed margins. They are typically greater than 3 cm wide. The marginal flowers are bell-shaped with enlarged irregular corollas. Flowers are typically blue, but can also be purple, pink, or white. Flowers are solitary at the end of a branched stem

Stem: Mature plants are 0.2 – 1.2 m tall. Stems are greyish-green, branched, erect, and loosely hairy.

Leaves: Are grey-green, matte, and lanceolate with narrow upper leaves and smooth edges. The lower leaves can be toothed or lobed along the margins. They can be up to 13 cm long and 1 cm wide.

Fruit: Are 4 – 5 mm long with fine, hairy bristles attached to one end. The seeds are typically straw-coloured.

Roots: Taproot.

Similar Species


Mountain Bluet (Centaurea montana) by Dave Steers

Mountain Bluet  (Centaurea montana) has thicker foliage and fewer flower petals.








Cupid’s Dart (Catananche caerulea)

Cupid’s Dart is a long-stalked flower with blue or purple jagged-edged flower heads.


Please report any sighting of Bachelor’s Button by clicking here.

Habitat and Origin

Bachelor’s Button is native to Southern Europe where it is known as ‘cornflower’ and is commonly found in grain fields. It is now considered endangered in its native habitat.

Bachelor’s Button prefers dry disturbed areas such as roadsides, riverbanks, meadows, fields, and grasslands.

Current Distribution

Propagation & Vectors of Spread

Bachelor’s Button reproduces through seeds. The plant produces copious amounts of seeds, which germinate very quickly, helping the plant spread aggressively.

Bachelor’s Button is spread by gardeners; it is often planted in gardens and is commonly found in wildflower seed mixes. It is also often found as a contaminant in crop seed. Moreover, seeds are spread by wind, water, and birds that eat the seeds.

Ecological & Economic Impacts


  • Outcompetes native vegetation in meadows and grassland habitats.
  • Decreases moisture and nutrients available in the soil.


  • Dense colonies invade grain fields and reduce crop yields.
  • Seeds can contaminate crop seeds.
What Can I Do?

Bachelor’s Button is currently found throughout the Sea to Sky Corridor, so the best approach to controlling its spread is by PREVENTION.


Learn to identify Bachelor’s Button: use the images presented in this profile page to learn how to identify Bachelor’s Button.

What to do if you spot it: You can report any Bachelor’s Button sighting by clicking here.



  • Regularly monitor properties for weed infestations.
  • Ensure soil and gravel are uncontaminated before transport.
  • Check wildflower mixes to ensure that they do not contain Bachelor’s Button.
  • Ensure that plants are disposed of in a garbage bag if found in floral arrangements to prevent seeds from spreading.



  • Do not unload, park or store equipment or vehicles in infested areas; remove plant material from any equipment, vehicles, or clothing used in such areas and wash equipment and vehicles at designated cleaning sites before leaving infested areas.
  • Do not plant Bachelor’s Button in a garden, no matter how well-contained its enclosure may seem.
  • Do not move soil that has been contaminated with Bachelor’s Button.
  • Do not compost




  • Repeated hand-pulling is the most effective way to control Bachelor’s Button, as long as the entire root system is removed.
  • Regular mowing or tilling can reduce weed progression; material can be left on-site to decompose if the plant has not started flowering yet.
  • Once Bachelor’s Button has flowered, all plant parts must be bagged and deeply buried at the landfill.
  • Deadheading (removing the spent flower heads) can limit the plant’s self-seeding tendencies.
  • When tilling, be sure to prevent machinery from spreading root fragments to new sites by washing it.


  • Plants should be treated when they are in the rosette stage.
  • Bachelor’s Button control has shown success when using a mixture of glyphosate and aminopyralid or glyphosate and clopyralid.
  • We recommend that any herbicide application is carried out by a person holding a valid BC Pesticide Applicator Certificate. Before selecting and applying herbicides, you must review and follow herbicide labels and application rates; municipal, regional, provincial and federal laws and regulations; species-specific treatment recommendations, and site-specific goals and objectives.


There are no biological control agents currently available for this plant.