Bachelor’s Button

Identification & Biology
Alias' : Cornflower
Latin Name : Centaurea cyanus
Category : Terrestrial Plants
Description :
  • Annual with erect stems up to 1m tall and a large taproot
  • Leaves are narrow and lance-shaped, up to 13 cm long with smooth edges
  • Flowerheads have bracts at the base and are pom-pom like, consisting of many smaller flowers
  • Flowers are typically blue to purple but can be pink or white and have fringed edges
  • Seeds are pale blue to straw-coloured and 4-5 mm long with fine hairy bristles on one end


Bachelor’s button can germinate in the spring or fall. When it germinates in the fall, the plant overwinters as a rosette and buds in the spring. Flowers bloom in May. Bachelor’s button produces large amounts of seeds which are shed in mid-summer.

Bachelor’s button may be confused with mountain bluet (Centaurea montana), another invasive plant. Bachelor’s button can be distinguished by its thin, sparse foliage and thick, full flowerheads compared to the thick foliage and thin flowerheads of mountain bluet. 
Look Alikes

Bachelor’s button grows best in sunny conditions with soils that drain well. This can include roadsides, riverbanks, meadows and fields. Bachelor’s button is native to southern Europe where it is considered endangered. It was introduced by gardeners as an ornamental plant and has now spread throughout Canada and the United States. Bachelor’s button continues to be commonly sold in wildflower seed mixes.

Impact & Risks
  • Can outcompete native plants in grasslands and meadows
  • Invades grain fields, reducing crop yields and contaminating seed crops
Prevention & Mitigation

The most effective way to ensure that your lands do not become infested with bachelor’s button is by prevention. Here are some recommendations to prevent invasion on your property:

  • Check the source and contents of wildflower mixes; some mixes contain invasive plants
  • Do not purchase, trade or grow bachelor’s button
  • Maintain your crops and natural lands in a healthy, vigorous condition to ensure a competitive plant community; competitive perennial grasses and forbs utilize water and nutrients that would otherwise be readily available to bachelor’s button
  • Regularly patrol your property for bachelor’s button plants and immediately control or remove infestations before seed set
  • Cooperate with adjacent landowners and encourage them to prevent bachelor’s button spread
  • Immediately re-vegetate disturbed, bare soils with an ecologically suitable seed mix that provides dense, early colonization to prevent invasive plant establishment
  • Do not move contaminated soils to a new area
Treatment & Disposal
  • Plants can be hand pulled or dug, ensuring as much taproot is removed as possible
  • Regular mowing or tilling before plants flower can reduce progression of the outbreak
  • Chemical control is also an option; before applying herbicide, read the label thoroughly to understand how to use safely and effectively
  • For further information on the selection and application of chemicals to protect your crop, contact Agri Service BC at 1-888-221-7141 or email
  • There are no biological controls (natural insect enemies) for bachelor’s button at this time
Okanagan Distribution

Priority Level Definitions

Watch For - Poses a significant threat (very high risk) and does NOT presently occur in the region OR is relatively new to the region and is very limited in extent.
High - High risk/impact; limited population with significant potential to spread in the region.
Medium - Medium risk/impact; limited distribution – broader population distribution with potential to spread further in a region.
Low - Low risk/impact; may be widespread or not, may be of concern in specific situations with certain high values – e.g. specific agriculture crops. Some species may be treated primarily with biological control agents.