Out of some 500 species, only a dozen or so are widely cultivated. Of these, annuals are grown mainly for cut flowers; perennial kinds are valued for soft, silvery foliage. All are relatively easy to grow. For best performance, add lime to acid soils. Sow seeds of annuals or set out plants of perennial kinds in spring or fall. (In desert regions, plant all in autumn for winter and spring bloom.)Centaurea montana
Native to mountains of central Europe. It forms a clump 1 1/2–2 ft. tall and wide; grayish green leaves reach 7 in. long. Flowers resembling ragged blue 3-in. cornflowers top the stems in late spring to midsummer. Protect from snails. Divide every other year.