Black-eyed susan flowers are one of the easiest wildflowers to identify. Bright yellow petals surrounding a black or brown "eye" bob over medium-green shallowly lobed leaves. You will often find black-eyed susans growing in abandoned pastures and along roadsides. Black-eyed susans flower in midsummer with blooms lasting into the first fall frosts. Plant them where they will receive plenty of light, and since black-eyed susans are not picky about soil, they can go almost anywhere in your garden. Black-eyed susans are often listed as rudbeckia or gloriosa daisies.
Plant black-eyed susan in spring after all danger of frost has passed or in early fall. You can start plants from seed or set out plants purchased from a nursery. Choose a spot in full sun to light shade (plants should receive at least 6 hours of direct sun a day). Black-eyed susans are not picky about soil. Working compost into the soil before planting brings soil up to the fertility preferred by black-eyed susans.
Prepare the planting site by mixing 3 to 4 inches of compost into the top 6 inches of soil.
Broadcast sow seeds over the planting site and press gently into the soil using the back of a hand trowel or shovel. Keep the seeds moist until they germinate.
Dig a hole just large enough for the root ball of black-eyed susan plants. Plant at the same depth it was growing at in the nursery.
Water black-eyed susan plants only during extended (three or more weeks of no rain) drought.
Fertilize black-eyed susan plants in midspring after growth has started by mixing 1 to 2 inches of compost into the soil around the base of the plant.
Prune or dead head (remove spent blossoms) to extend the blooming season. Cut flower stalks as close to the crown of the plant as possible. Remove tattered or dead leaves at any time during the growing season.
Divide perennial black-eyed susan plants every 3 to 4 years. Dig up the clump in early or midfall. Use your shovel to break the clump into 2 to 4 inch pieces. Replant, compost or give away the divided pieces.
Use 1 to 2 inches of organic mulch around the base of black-eyed susan plants. Mulch reduces weeds, keeps the soil moist and protects the roots of the plant during winter from frost damage and heave (exposed roots during freeze/thaw cycles). Replace or refresh mulch every fall.