Facts on Black-Eyed Susan Flowers

Although the characteristic yellow flowers of black-eyed Susans are frequently seen along highways and roadsides, they are also easy to grow in the home garden. They are tolerant of cold and drought and are also insect-resistant, which makes them ideal for a low-maintenance flower garden.

Although their flowers are almost identical in appearance, there are actually two general categories of black-eyed Susans. Native black-eyed Susans are wildflowers that can grow as high as 5 feet, which is much taller than the cultivated black-eyed Susan. Cultivated black-eyed Susans are the most common type in nurseries, although native varieties have become more common. Because their growth requirements are similar, you may be able to grow both varieties in your garden, which will increase the length of the flower blooming period.

Black-eyed Susans need full sunlight and thrive in well-drained, fertile soils. Black-eyed Susans have an 80 percent rate of growing success, according to Texas A&M University Extension. If you plant black-eyed Susans from seed, allow about seven to 30 days for the germination period. Seeds germinate best at 70 degrees Fahrenheit. Loam soils are ideal for black-eyed Susans. Allow plenty of space between plants to avoid pests and fungal diseases. Although some black-eyed Susans can be used as biennials or perennials, they are most commonly grown as annual in flower gardens, according to the University of Illinois Extension.

Black-eyed Susans bloom in the late summer months, usually between June and August. They may continue to hold their flowers until early fall. The flowers can be cut and have a long vase life of six to 10 days. Black-eyed Susans are ideal for a grass border because they thrive in full sunlight, as noted in "Southern Sun." Native black-eyed Susans bloom a bit later than cultivated varieties, and usually bloom for about two to three months. After the blooms fall off, you can allow the seedheads to remain on the plant if you want to attract birds to your garden or lawn.

The black-eyed Susan is Maryland's state flower, although it is not actually native to the state. The famous Preakness races, held annually in Maryland, have come to be known as the Run for the Black-Eyed Susans because the winning horse is draped with a blanket made of the flowers. The plant's Latin name, Rudbeckia hirta, means "rough hairy," which refers to the seedhead. The black-eyed Susan symbolizes encouragement. The flowers are native to Illinois, Indiana, Iowa, Michigan, Missouri, Ohio and Wisconsin.