The showy garden rudbeckias that brighten summer and fall borders are descended from wild plants native mainly to the eastern U.S. All are tough and easy to grow. Blossoms have yellow or orange rays and a raised central cone. Choice cut flowers; cutting also encourages rebloom late in season. Divide perennials when crowded, usually every few years.
R. auriculatus. EARED BLACK-EYED SUSAN. Perennial. Zones MS, LS, CS, TS; USDA 7-10. Native to moist areas of southeastern Alabama and nearby Georgia and Florida. Grows 6 ft. high. Golden yellow flowers are 2 to 3 in. wide. Often needs staking. Takes alkaline soils.
R. fulgida. YELLOW CONEFLOWER. Perennial. Initially 3 ft. tall, 2 ft. wide; after a few years, spreads by rhizomes to form a larger clump. Branching stems; broadly lance-shaped, 5-in.-long, hairy, dark green leaves. Yellow, 2- to 2-in.-wide flowers with a black to brown central cone bloom in summer. Selections are more often grown than the species. Among the most popular is R. f. sullivantii 'Goldsturm', bearing 3-in., black-eyed yellow flowers on 2- to 2-ft. stems. Some nurseries offer the taller, more variable seed-grown Goldsturm strain. 'Early Bird Gold' has an especially long bloom season, running spring to fall.
R. f. speciosa (R. speciosa), to 2 ft. high and 2 ft. wide, is native from New Jersey to Alabama and Georgia; it has bright orange-yellow petals surrounding a black cone. Its selection 'Viette's Little Suzy' is a dwarf to about 14 in. high and wide, with dark-eyed yellow blooms.
R. hirta. BLACK-EYED SUSAN, GLORIOSA DAISY. Biennial or short-lived perennial; often grown as annual because it blooms the first summer from seed sown in early spring. Zones US, MS, LS, CS, TS; USDA 6-11. To 34 ft. tall, 1 ft. wide, with upright, branching habit. Stems and lance-shaped leaves to 4 in. long are rough and hairy. Daisylike, 2- to 4-in.-wide flowers have orange-yellow rays and a prominent purplish black cone. Not usually browsed by deer.
'Indian Summer' produces 6- to 9-in., single to semidouble flowers in golden yellow. 'Irish Eyes' ('Green Eyes') has 2- to 3-in., golden yellow flowers with a light green central cone that ages to brown. 'Prairie Sun' has golden petals with light yellow tips surrounding a pale green cone. 'Denver Daisy' bears large (68 in.) yellow flowers with a dark cone and a large burgundy eye. It is a heavy bloomer that reaches 2226 in. tall. 'Cherokee Sunset' has semidouble to double flowers (34 in.) in a range of yellow, orange, red, bronze, and mahogany. It grows 23 ft. tall.
For front of border, try lower-growing selections 'Goldilocks' (double flowers) and 'Toto', both 810 in. high; Becky Mix (1215 in.); 'Sonora' (15 in.); 'Tiger Eye' (1624 in. high and wide, with unusually profuse bloom), and 'Marmalade' (2 ft.).
R. laciniata. CUTLEAF CONEFLOWER. Perennial. The species grows 10 ft. tall, 4 ft. wide; it has light green, deeply lobed leaves to 4 in. long and blooms from summer to fall, bearing 2- to 3-in.-wide flowers with drooping yellow rays and a green cone. Very heat tolerant. More widely grown in gardens are the following three selections. 'Golden Glow' ('Hortensia'), to 67 ft. tall, is an old favorite that bears bright yellow double flowers 23 in. wide. Good summer screen or tall plant for back of borders. Does not seed, but spreads rapidly (sometimes aggressively) by underground stems. 'Goldquelle', with double blooms in lemon-yellow, is a less aggressive form growing 3 ft. tall, 1 ft. wide. 'Autumn Sun' ('Herbstonne', often listed as the similar native R. nitida) grows to 6 ft. tall, 2 ft. wide; bears single, 4- to 5-in.-wide flowers with yellow rays and a bright green cone that ages to yellow.
R. maxima. GREAT CONEFLOWER. Perennial. Large (to 5-in.) bluish gray leaves form a mound to 23 ft. tall and wide. In midsummer, 5- to 6-ft. stems bear flowers to 3 in. across, with a prominent brown central cone and drooping yellow rays. 'Golda Emanis' combines golden foliage that fades to chartreuse as it blooms, producing golden, daisy-like blooms on 7 ft. tall stalks.
R. triloba. BROWN-EYED SUSAN. Biennial or perennial. To about 4 ft. tall and as wide, with stiff, much-branched stems and 5-in.-long leaves, some deeply lobed. Blossoms to 3 in. wide, with yellow-orange rays and dark brown-purple centers. Can be weedy looking. 'Prairie Glow' has large, bicolored, yellow and orange-red blooms that make great cut flowers.