Yellow Coneflower (Ratibida columnifera) Yellow coneflower is a quick growing, early invader of disturbed areas on the prairies. It is more common in mixed-grass prairies, but is found regularly in drier parts of the tall-grass. It blooms in mid-July, often producing many "hat-shaped" blooms borne on leafy stalks that reach to about 40 cm. This is an easy to grow wildflower, but individual plants seldom live more than 3-4 years.