Black-eyed Susans are wildflowers that grow in the prairie and along roadsides but have been domesticated for home gardens. Known scientifically as Rudbeckia, there are many different varieties available. Butterflies are attracted to this plant and they make an attractive addition to any garden.
Rudbeckia produces yellow, gold, orange and red petals that radiate from a central black or brown disc. They are daisy-like in nature. Depending on the variety, they can grow from 1 to 4 feet in height and have a bushy manner that can reach 12 to 18 inches in diameter. Some varieties are annuals that only grow one season but will reseed, and the seeds will sprout the next growing season. Biennial types grow for two years. The first year there are usually no flowers or the plants only produce the central disc then the next year the full flower appears. There are also perennial varieties that come back year after year. All Rudbeckia are long-blooming and flower all summer and into the fall.
Soil needs to be well-drained but have the ability to still stay moist for Black-eyed Susans. Too much water will cause the roots to rot, and too little water will make them wilt. They love to be planted in full sun but will tolerate partial shade as well.
Black-eyed Susans can be planted from seed directly in the ground in late spring. Seeds can be scattered in an area and lightly covered with soil. Once they sprout, thin to 12 to 18 inches apart. Transplants can also be planted from divisions in the spring or early summer. Smaller varieties work well as a border, while the taller types should be planted against a wall or fence to keep them from drooping or breaking off in the wind.
Black-eyed Susans need regular watering and should never completely dry out. Supplement water during dry periods. Remove flowers when they die and turn brown. This will promote more blossoms. They usually do not need any fertilizing because they grow like weeds, but if they look sparse they can benefit from a little flower fertilizer.
Perennial Rudbeckia gets bigger every year and, if not divided every two or three years, the centers will start to die out. Dig up the whole plant and cut the roots in two to three sections with a sharp knife. Replant the sections as soon as possible and give what you do not need to a friend.
Rabbits love Black-eyed Susans, especially when they are young. Protect them with chicken wire wrapped about 5 to 6 inches up the base of the plant, or plant French marigolds around them; rabbits do not like the smell or taste of French Marigolds and will stay away if planted near Rudbeckia. Aphids and slugs will make a meal out of Black-eyed Susans. Grow chives or garlic near them to keep aphids away, and place construction sand around the base of the plants to deter slugs.