The black-eyed susan is a flowering black and yellow plant with curving leaves. It is culturally important in the Southern U.S., and is often used to attract butterflies to gardens. It long ago spread throughout North America and much of the world. Black-eyed susan is the state flower of Maryland and was important in the history of the University of Southern Mississippi.
| Common name | Black Eyed Susan, Black-eyed Susan, Gloriosa Daisy |
| Botanical name | Rudbeckia hirta |
| Family | Asteraceae |
| Species | hirta |
| Origin | Eastern United States, NC |
| Life cycle | Biennial |
| Plant type | Annual |
| Hardiness zone | 3, 4, 5, 6, 7, 8 |
| Sunlight | Full Sun |
| Maintenance | Low |
| Soil condition | Clay |
| Soil ph | Acid |
| Drainage | Well-Drained |
| Growth rate | Fast |
| Spacing | Less than 12 in. |
| Harvest time | Fall |
| Flowering period | Spring |
| Height | 2 ft. – 4 ft. |
| Width | 2 ft. – 4 ft. |
| Flower color | Gold, Yellow |
| Leaf color | Green |
| Fruit color | Brown, Copper |
| Stem color | Green |
| Fruit type | Capsule |
| Flower benefit | Good Cut |
| Garden style | Butterfly Garden |
| Uses | Coastal |
I. Appearance and Characteristics
Rudbeckia hirta, commonly called black-eyed Susan, is a North American flowering plant in the family Asteraceae, native to Eastern and Central North America and naturalized in the Western part of the continent as well as in China. It has now been found in all 10 Canadian Provinces and all 48 of the states in the contiguous United States.
Rudbeckia hirta is the state flower of Maryland.
The specific epithet hirta is Latin for “hairy”, and refers to the trichomes occurring on leaves and stems. Other common names for this plant include: brown-eyed Susan, brown betty, gloriosa daisy, golden Jerusalem, English bull’s eye, poor-land daisy, yellow daisy, and yellow ox-eye daisy.
Rudbeckia hirta is an upright annual (sometimes biennial or perennial) growing 30–100 cm (12–39 in) tall by 30–45 cm (12–18 in) wide. It has alternate, mostly basal leaves 10–18 cm long, covered by coarse hair, with stout branching stems and daisy-like, composite flower heads appearing in late summer and early autumn. In the species, the flowers are up to 10 cm (4 in) in diameter, with yellow ray florets circling conspicuous brown or black, dome-shaped cones of many small disc florets. However, extensive breeding has produced a range of sizes and colors, including oranges, reds and browns.
The species is toxic to cats when ingested.
II. How to Grow and Care
Sunlight
You will get the best flowering from your black-eyed Susans in full sun, but they can handle partial shade.
Temperature and Humidity
As a tough summer performer, this plant likes warmer temperatures of 60 degrees Fahrenheit and more. It handles both drought and humidity well, but it does need good air circulation to avoid powdery mildew.
Watering
Black-eyed susan is adapted to grow in drought conditions, but to ensure that your plant grows well you should water it during dry periods. Be sure to only water the plant when the surrounding soil is dry since overwatering will cause it to rot. Also, water the plant only at the base, since it is prone to damp-related diseases.
Soil
Black-eyed Susans are not particular about soil. They do best in soil that is not too rich and is well-drained, with a pH around 6.8.
Fertilizing
Black-eyed susan gets all the nutrients that it needs from the soil and water, so it doesn’t require the addition of any artificial fertilizers to thrive. However, using mulch on the surrounding soil is a great way to retain moisture and introduce nutrients naturally.
Pruning
Deadheading black-eyed Susan is essential for healthy regrowth. When deadheading, cut back to just past the first leaf on the stem. Cut them back to 2 inches above the ground at the end of the season. Add mulch during cold months to keep them from freezing before spring. Black-eyed Susan propagates from underground rhizomes and self-seeds, so if you want to keep them from becoming invasive, clean up seed pods and trim back growth.
Propagation
Rudbeckia hirta is a relatively short-lived perennial that might not get old enough to form large, dense clumps. But if it does, it can be divided for propagation in early spring, just as new growth appears, or autumn, when the plant has finished flowering:
- Lift the entire plant out of the ground with a shovel. Divide it in half or more sections using pruners or a spade.
- Replant each section in a new location and keep it well-watered until you see new growth in a few weeks.
- Since black-eyed Susans easily reseed themselves, you might automatically have new plants in your flower beds next year.
How to Grow from Seed
To get a head start on the growing season, start black-eyed Susans indoors from seed about 10 weeks before the last expected frost. Plant seeds 1/4 inch deep in trays or pots filled with a moistened seed starting mix. Perennial varieties will germinate best if the seed containers are kept in the refrigerator or a similarly cold place for four weeks after seeding. Afterward, soil temperature needs to be warm for germination, so place the seeded tray or pot on a heating mat or a warm space such as the top of the refrigerator or a table above a heat vent. Seeds should germinate within 7 to 21 days. Harden off the seedlings before planting them outside. Make sure all danger of frost has passed before planting outside.
Black-eyed Susans can also be direct seeded in the garden once daytime temperatures remain around 70 degrees. Scatter seeds. cover lightly with soil, and water well. Keep soil moist. Thin seedlings to 6-12 inches apart for dwarf varieties, 18-30 inches apart for larger cultivars. If you do not wish to start your own seed, seedlings and plants can be purchased and transplanted.
Pests and Diseases
Common Pests & Plant Diseases
Black-eyed Susan is rarely bothered by serious pests and diseases. Septoria or angular leaf spots are two fungal diseases that form black spots on the leaves and stems. Provide good air circulation by leaving ample space between plants, and avoid getting the leaves wet when watering as that can spread the fungi. Removing and throwing infected leaves in the trash instead of composting helps to contain the spread.
Common Problems with Black-Eyed Susan
Powdery mildew can affect the leaves in hot, humid conditions. Minimize this by planting in full sun, and thinning the plants to allow for good air circulation.
III. Uses and Benefits
- Maryland state flower
The black-eyed Susan was designated the state flower of Maryland in 1918. In this capacity it is used in gardens and ceremonies to celebrate, memorialize and show affection for the state of Maryland and its people. The Preakness Stakes in Baltimore, Maryland, has been termed “The Run for the Black-Eyed Susans” because a blanket of Viking Poms, a variety of chrysanthemums resembling black-eyed Susans, is traditionally placed around the winning horse’s neck (actual black-eyed Susans are not in bloom in May during the Preakness).
- University of Southern Mississippi
In 1912, the black-eyed Susan became the inspiration for the University of Southern Mississippi school colors (black and gold), suggested by Florence Burrow Pope, a member of the university’s first graduating class. According to Pope: “On a trip home, I saw great masses of Black-Eyed Susans in the pine forests. I decided to encourage my senior class to gather Black-Eyed Susans to spell out the name of the class on sheets to be displayed during exercises on Class Day. I then suggested black and gold as class colors, and my suggestion was adopted.”
- Butterfly attractant for enhancing gardens
Butterflies are attracted to Rudbeckia hirta. It is a larval host to the bordered patch, gorgone checkerspot, and silvery checkerspot species.
- Mosquito control by dragonflies
Dragonflies, voracious eaters of mosquitoes, are attracted by the tiny pollinators of these flowers.
- Traditional Native American uses
The plant is thought to be an herbal medicine by Native American for various ailments. The roots but not the seedheads of Rudbeckia hirta can be used much like the related Echinacea purpurea with unsubstantiated claims to boost immunity and fight colds, flu and infections. The Ojibwa people used it as a poultice for snake bites and to make an infusion for treating colds and worms in children.
IV. Harvesting and Storage
- Flowers
Cut flowers for display just before buds completely open. Use large blooms as centerpieces and smaller ones as accents. Change the water every day to keep them fresh. Vase life is 8 to 10 days.
- Seeds
Once the seed heads are dry and brown, it’s time to clip some stems. Pop off the seed heads from the stems and toss them in a small jar; close the lid and shake it to loosen the seedheads. Then, dump the seed heads from the jar into a sieve with a white piece of paper below it. Break up the seed heads in the sieve with your fingers. The seeds will come off and fall through the sieve onto the paper! Fold the paper in half and carefully funnel those seeds into a paper envelope. Close and label the envelope and store it in a cool, dry place.
Find Where to Buy the Best Black Eyed Susan (Rudbeckia hirta)
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