Black-eyed Susan (Rudbeckia hirta) is a low-maintenance plant that showcases daisy-like blooms throughout summer and into fall. With more than 20 black-eyed Susan varieties, there are a range of sizes available. Black-eyed Susans are typically grown as annuals in cold-winter areas but can be short-lived perennials or biennials in areas with mild winters. The varieties highlighted are recommended for U.S. Department of Agriculture plant hardiness zones 4 through 9 unless otherwise indicated.
The black-eyed Susan variety "Toto" reaches 8 to 9 inches tall with a spread of 12 to 18 inches. The flowers have yellow petals with a dark center and appear from midsummer through early fall. This species prefers full sun and tolerates dry soil conditions, although regular water encourages a longer bloom season.
"Becky" is a variety that can reach 9 to 18 inches tall and spread 24 to 30 inches. This species will grow in part shade to full sun with dry soil. The blooms are yellow with a dark center. "Sonora" is another medium-height variety. It grows 12 to 14 inches tall and can spread 12 to 18 inches. The blooms on this variety are red and yellow. Both of these varieties bloom from midsummer through early fall.
"Irish Eyes" grows up to 36 inches tall and can spread 24 to 30 inches. The blooms on this variety are a bit different than the others. The petals are orange and the center is green. Towering over the other varieties is "Indian Summer." This plant can grow 36 to 48 inches in height and 24 to 36 inches wide. The blooms are the traditional yellow with a dark center. Both of these taller varieties bloom during summer and early fall and tolerate full sun and dry soil.
Black-Eyed Susan Vine
While black-eyed Susan is a North America native, the black-eyed Susan vine (Thunbergia alata) is not. This tropical plant was named for its flowers, which have yellow or orange petals and dark centers, resembling the herbaceous perennial. Black-eyed Susan vine can reach 6 to 8 feet tall and blooms from early summer through mid-fall. It prefers part shade to full sun and moist, well-drained soil. This is a frost-tender plant and is recommended for USDA zones 10 through 11. In colder climates it is classified as an annual.