Centaurea

Botanical/Latin
   Centaurea

Pronunciation
   sen-taw-ree-ah

Common Name
   Bachelor Button, Cornflower

Hardiness zone range
   3 - 7

General Comments
Centaureas are hearty, robust perennials with large, thistle-like, usually solitary flowers carried above attractive, grayish-green foliage in early summer and summer. Representing a huge group (almost 500 species worldwide), we list the two types that are the best suited to our garden conditions.

Uses
They are valuable additions to mixed beds with shrubs and conifers where they can be used to add color and stature to the display. In perennial borders, the showy flowers add height to lower growing perennials, and since they are excellent cut flowers, they can be cut and brought indoors to make attractive, long lasting arrangements. They are vigorous and naturalize well in wildflower areas. Birds love to eat the seeds; in areas where the re-seeding is acceptable, flower heads can be left to set seed to provide a food source for winged visitors.

Light Preference
Sun to partial shade. They tolerate and grow well in sun or shade, but the brighter the conditions the shorter and stockier the growth; avoid lanky floppy growth by giving them as much sun as possible.

Culture
Easy plants to grow, all they need is an ordinary soil that is well drained and does not become waterlogged. They occur in nature in open woodland areas, on rocky slopes, and in grassy, open areas on mountain sides. Rich fertile soils are not needed, but free draining ones are. In garden beds and borders, the old flowering stems should be cut back hard (see Splendor Suggestions for details). They will happily grow and flower for years without needing to be divided. If clumps become too large or look like they are losing vigor, they can be lifted and divided by chopping them into transplantable pieces with a sharp spade and replanted about 18 inches apart. The best time to do this is either early spring before growth commences, or in autumn as they are preparing to go into winter dormancy.

Background
The botanical name comes from centaurs, Greek mythological figures with a man's upper body but a horse's lower half. They are supposed to have used the flowers medicinally to heal. The species names also have botanical Latin meanings, which are descriptive and make sense when understood. The dealbata part of Centaurea dealbata means whitened, referring to the undersides of the leaves. While in the other species, Centaurea montana. it simply means mountains, referring to the natural habitat. The common names originate from old English country names. Cornflower comes from an annual blue flowering species that grew with crops and was in flower at harvest time, whereas Bachelor's Buttons is from their resemblance to the old style, cloth buttons that were used to fasten early garments. The Bachelor part is more intriguing! Robert Greene wrote in 1592, "I saw the Bachelor's buttons, whose vertue it is to make wanton maidens weepe when they have worn it for fortye weekes under their aprons for a favour". Perhaps we should leave it to you to figure it out!

Splendor Suggestions
When the first flush of flowers ends in early summer, old flowering stems should be removed to encourage fresh growth and repeated flowering. This also prevents them self-seeding, stimulates new basal growth, and maintains vigor in the clumps. If the stems and foliage become floppy and look ragged, shear the clumps back to ground level. They will quickly regenerate, flowering again in late summer and autumn.

Companion Plants
They combine well with the silvery foliage of Artemisias and lavender-blue flowers of Catmint, Nepeta 'Blue Wonder' or 'Dropmore'. The big, white daisy shaped heads of Leucanthemums or the frothy flowers of Gypsophila provide good support while the fringed, deep blue flowers of C. montana look nice when set in a soft green, ground cover mist of Alchemila mollis (Lady's mantle), or beside the light yellow spires of Digitalis grandiflora.