For a hardy perennial that blooms all summer long, few flowers are more reliable and widespread than the black-eyed Susan (Rudbeckia fulgida). The flowers resemble daisies, except the centers are dark brown and the petals are golden yellow. Black-eyed Susans have hairy stems and rough leaves. This is the state flower of Maryland and is a widespread wildflower throughout the United States, notes Texas A&M University.
Black-eyed Susans grow best in full sun and well-drained soil. These flowers are not particular about the soil pH or the type of soil, as long as the soil drains adequately after rain. These perennial flowers will spread, so select a location that offers them room to sprawl or plan to divide them frequently.
Plant black-eyed Susans from seed or from transplants. Sow seeds in the late spring after all danger of frost passes at a depth of 1/16 inch. Cover with soil and keep the garden bed moist for 15 to 30 days until the seeds germinate.
To plant transplants, dig holes in your garden bed twice the size of the transplant's rootball and remove rocks and weeds. Take the plants out of their plastic containers and place one in each hole. Holding the stem straight, backfill the hole with soil. Water the garden bed until the soil becomes saturated.
Black-eyed Susans are forgiving of harsh treatment but do best when watered deeply every time the soil dries out. To test the soil's moisture stick a finger down into the soil. If it feels moist or clammy, withhold water. When it feels dry and crumbly, water until it becomes saturated.
These perennial flowers bloom from July to October, making them long-lasting summer flowers.
Cut down black-eyed Susan stems to 1 to 2 inches above ground in the fall when the blooms pass. This prevents fungus or garden pests, such as snails, from taking refuge in the dried-out plant stalks. Black-eyed Susans will reseed each year, according to the University of Illinois. Divide your black-eyed Susan patch when it becomes too large. Dig up some plants in the spring when they reseed. Relocate to another area of your garden or compost them if you only want to maintain one bed.
Black-eyed Susans grow in USDA hardiness zones 3 to 9.