Very popularand perennials which are , although the perennial varieties of Rudbeckia (Echinacea) purpurea prefer a soil that does not dry out too readily. The genus is sometimes referred to as coneflower by reason of the cone-like centre on the individual blooms.
Among thevarieties which may be sown outdoors in early May and thinned to about 10 in. apart, My Joy has extra large, orange yellow 5 in. across with a small black centre, to about 2 ft. Kelvedon Star is about the same height, deep yellow with a mahogany zone and velvety-brown disc. Autumn Leaves is a strain embracing red, bronze and bronze tints. Although really perennial (if short-lived) it is better treated as a half-hardy annual, a March giving a profusion of bloom from July to October.
The tallest of the perennial rudbeckias, which mostly bloom in late summer and early autumn, are varieties of Rudbeckia laciniata and attain 6 ft. on moist soils. Golden Glow has fully double yellow flowers, Golden Globe is a lighter yellow. Like all rudbeckias, they are excellent for, the long making decorative an unusually pleasant task. R. nitida Herbstsonne is again yellow with prominent green cones and glossy green foliage. R. speciosa (newmanii) is the old-fashioned Black-eyed Susan, yellow with striking black centres, to about 2 ft. It is happiest in moist soil. R. deami is more orange, more bushy and a little taller than R. speciosa. R. Goldsturm is in bloom over a longer period than speciosa or deami.
R. purpurea, more correctly Echinacea purpurea, reaches 4 ft. on a cool soil. Its varieties include Abendsonne (carmine-crimson), Karl Seibert (rosy-red) and The King (crimson-purple). All the above are increased by division in spring.