The perennial black-eyed Susan is native to the United States. The plant is a wildflower that is planted in gardens, open fields and along roadsides. The state flower of Maryland has a brown-domed center with yellowish-orange flower petals around the dome. Black-eyed Susan plants are forgiving plants when neglected and will grow 2 to 3 feet tall.
Sow the seeds when soil temperatures are at least 70 degrees Fahrenheit. It takes seven to 30 days for black-eyed Susan seeds to germinate when sown 1/16 inch deep in the soil. Plants will bloom from June to August after germination and growth. Black-eyed Susan will grow in any soil, but sandy, loamy soil that has good drainage is the best.
Black-eyed Susan plants are sun-loving plants that will survive in any heat. Plants can tolerate low, medium and high humidity without any adverse effects on the plant and flower. Temperatures will not affect the black-eyed Susan, but green foliage will die back after the first frost.
Black-eyed Susan plants should be deadheaded when the flower is dried up and not before. After the flower blooms and dies back, the flower dries up and drops its seeds into the ground below. Even in cold, harsh winters, the seeds will make it through the winter and start growing the next spring as long as the soil is not disturbed. After the seeds have dropped, remove spent flowers from the plant.
Add slow release fertilizer to the soil every four months, but the black-eyed Susan will flourish even without fertilizer. In spring, remove the dead foliage from the plant to encourage new growth. Black-eyed Susan plants are drought tolerant, but irrigate the soil when the plant goes longer than one week without rain in a home garden.