Common Names #
Black-Eyed Susans, Brown Betty, Marguerite Jaune, Hairy Coneflower, Gloriosa Daisy, Yellow Ox Eye, Brown-Eyed Susan, Yellow Daisy, Golden Jerusalem, Poorland Daisy
About This Plant #
Rudbeckias, commonly called Black-Eyed Susans are cheerful and hearty, golden-yellow garden staples. They are short-lived perennials, often treated as annuals, and self-seed prolifically, making an appearance year after year. Rudbeckias are fast-growing. They reach two to three feet tall and form clumps that spread to about one or two feet wide. They are members of the Asteraceae family, as are the Daisies and Sunflowers that they bear a resemblance to. They are hardy in USDA zones 3-9.
Rudbeckias are easy to establish and naturalize well, requiring little upkeep other than deadheading. They are a welcomed sight in everything from wildflower beds to urban lots. They make great cut flowers due to their strong stems and long-lasting, bright, colorful blooms. Their seed heads hold up well and continue to look attractive in arrangements, even after their petals have faded. Rudbeckia was declared the plant of the year in 2008 by the National Garden Bureau which led to the development of an impressive array of cultivars that come in all colors, heights, and forms. Rudbeckias are one of the most popular wildflowers grown They are ideal for mass plantings in naturalized areas, in the background of perennial beds, in borders, or in containers. The Black-Eyed Susan is also the state flower of Maryland.
Rudbeckias are native to North America. They can be found in natural areas, often blanketing open fields, and along roadsides from the Midwest to the Southwest including Texas, New Mexico, Colorado, and California. Their native habitat is in both damp woodlands and dry prairies. In the West, they grow from 5,000 to 8,500 feet along streams and wet places.
Rudbeckias have bright yellow petals that form around a dark, prominent, raised center disk that is black, brown, or maroon in color. They are Daisy-like in appearance with showy, two to three-inch wide blooms that last for many weeks. They will flower their first Summer, appearing at the height of summer, often when most other flowers are starting to fade, and last all through the late Summer until the first frost in early Fall. Their blossoms illuminate landscapes and attract a continuous procession of pollinators. Their leaves are scratchy and hairy, alternate, and are up to six inches long. They are deeply lobed or palmate at the base and gradually become simpler towards the flowers. They are sometimes freckled with purple spots. While the sandpaper-like leaves aren’t one of their best features, they do help to keep the pests away. Rudbeckia stems are sturdy and erect. Their rhizomatous roots produce colonies that can become quite large.
Rudbeckia hirta is one of the most commonly known species of the Rudbeckia genus. There are about 25 species of Rudbeckia and all are native to North America. They range in size from dwarf (about one foot tall) to giant (about nine feet tall). Most Rudbeckias are perennial while others are biennials or annuals. They self-sow readily though, returning each Spring from seed that was dispersed the previous Fall.
Rudbeckias are also called Coneflowers because of their cone-shaped seed heads. They are one of at least three other genera within the Asteraceae family that are commonly known as Coneflowers and should not be confused. The other flowers commonly known as Coneflowers are Echinacea, Dracopis, and Ratibida. Linnaeus named the Rudbeckia genus in honor of his patron and fellow botanist at Uppsala Univerisity, Olof Rudbeck the Younger (1660-1740) as well as Rudbeck’s late father Olof Rudbeck the Elder (1630-1702), who was a distinguished Naturalist, Philologist, and Doctor of Medicine as well as the founder of Sweden’s first botanic garden. The species name, hirta, comes from the Latin hirsutus, meaning “covered in hair”.
Rudbeckias are hearty flowers. While they are deer-resistant once their leaves become coarse and hairy, the tender young growth may get nibbled. Caterpillars, including Cabbage Moths and Dot Moths, may nibble them as well. The flowers are loved by bees and butterflies and they attract beneficial insects too. The seeds are loved by birds. Powdery mildew can be an issue, especially in hot, humid conditions. You can minimize the threat of this by planting Rudbeckias in full sun and ensuring the plants get thinned to allow for good air circulation.
Rudbeckias are easy to grow from seed. If direct sowing them outside, wait until the soil temperatures have warmed and ambient air temperatures are maintaining at least 60 degrees Fahrenheit to ensure good germination. Seeds can be started indoors ten weeks before the last anticipated frost date. Seeds can be scattered and gently pressed into the soil or covered with a very light layer of soil. Keep the seedbed moist. Germination should happen in about 10-15 days but will be slower if the soil temperatures are cooler.
Rudbeckias can to thinned or transplanted about 12-15” apart. Be sure to acclimate seedlings to outdoor growing conditions gradually if started indoors.
Rudbeckias will flower best in full sun but can handle partial shade as well. They can tolerate moist to dry growing conditions (once established) as long as the soil is well-draining. They can tolerate drought better than they canl soggy ground, just make sure the soil doesn’t get baked dry. They can tolerate a large variety of tough soil types but do best when the soil is compost-rich. Avoid too much fertilizer as this will result in weak stems and plants. Allow for adequate spacing around plants to allow good air circulation and to minimize issues with powdery mildew.
Regular deadheading of the spent flowers will keep the plants blooming longer. Allow at least some of the last flowers of the season to remain in order to go to seed to feed the birds and to ensure a good amount of self-seeding. The plants can be cut back after they flower to encourage a second smaller round of blooms later in the Fall. Rudbeckias form clumps but they typically do not die out in the center of the clumps so they don’t require frequent division. If your clump is getting too large, powdery mildew is an issue, or you want to make more plants, feel free to divide the clump. After the flowering season ends, the stems can all be cut back to two inches from the ground.
Seed Harvest #
Seed heads can be collected once they turn grey and begin to split open, revealing the mature seeds inside. Cut the seed heads off, leaving about six inches of stem. Place the seed heads into a paper bag, grasping the stem, and shake it vigorously. The seeds will fall out into the bag. You may have to break apart the seed head with your hands to loosen the seeds. If you wait to collect the seedheads for too long, the seeds will be scattered on the wind or eaten by birds. The collected seeds and plant material can be passed through a sieve or winnowed to separate the chaff.
Plant Uses #
- Yellow Dye can be obtained from the flowers
- Naturalized plantings, Xeriscaping, Borders, Containers
- Cut flowers
Culinary Uses #
Rudbeckia is not a popular plant in the kitchen. Reportedly, the young stems can be eaten like celery and the young greens are edible. The sap may cause skin irritation though, so exercise caution. The seeds are considered poisonous however and the plant is considered poisonous to various pets and livestock.
Medicinal Uses #
The roots and leaves of Rudbeckia have been used traditionally for a number of ailments. The root has been used to rid the body of parasitic worms, poultices have been used for snakebites, and the extracted juice from the roots has been used to treat earache. The plant also has diuretic properties.
Native American tribes also used Rudbeckia to treat colds. This application is one in which the scientific community has gone on to study in-depth. It appears that at least several species of Rudbeckias have immunostimulatory activity similar to Echinacea, which is a close relative. One particular study found that a root extract of Rudbeckia hirta had a stronger immunostimulating effect than the extracts from E. angustifolia and E. gloriosa. In other words, Rudbeckia may be even more effective against colds and flu than Echinacea.
Rudbeckia is native to the central United States and is distributed over most of the U.S. and parts of Canada.