Black eyed susans grow best in zones 3-11. These flowering plants, 1-5 x 1 m with many twining stems, need full sun or light shade. It is half-hardy, needing fairly warm conditions with protection, young plants can survive some frost. In cold areas treat it as an annual. (1) The leaves are heart or arrow-shaped, softly hairy and sometimes toothed. Many flowers are borne singly in leaf axils with a small calyx enclosed in 2 large, ridged bracts. The corolla is obliquely trumpet-shaped and is usually bright orange in wild plants. The inside of the tube is a striking dark maroon or purplish black. Nurseries also have variants with white, cream- or peach-colored, yellow to deep orange or nearly red flowers. The fruit is like a bird's head with a spherical base and a long 'beak'. Seed germinates easily in a damp mixture of fine humus-rich soil with some sand. A glass sheet on top helps keep the soil moist but do allow some air to circulate and newspaper on top of the glass will help germination by keeping the seeds dark.
Mature plants may have seedlings underneath ready for transplanting. Water the plant well at first and then moderately all year but especially in summer. Add compost at planting time and again 2 or 3 times per summer, as a mulch. (1) Black-eyed susan grows quickly and starts flowering at an early age. This plant flowers all summer but can continue all year in warmer areas. It can be trimmed if it gets too big but it is usually well behaved. Light trimming in spring will encourage flowering. If frost is a problem, cut the plant right back and it will probably resprout. Caterpillars may be a problem, but the plant usually has enough leaves to satisfy them (the butterflies and moths are a bonus anyway!) If necessary try to remove the insects by hand or use a soap solution. (1)
Black-eyed susan is probably pollinated by bees. An insect visiting the flower will touch the stigma first, with its back, and then the anthers, getting a load of pollen that is then carried to another stigma. The flowers reflect ultraviolet light in a pattern that is visible to insects but not to humans. This helps insects find the centre of the flower. A butterfly, Junonia ovithya, or the eyed pansy, and moths also visit these plants to lay eggs, for the larvae eat the leaves. Hence this creeper, being attractive to insects, helps bring birds into a garden. Birds also often nest in the thickly tangled stems. Used mainly as an ornamental plant, Thunbergia alata makes a good screen when used to cover unsightly dead trees or walls. It needs some support (fences, trellises, arches, arbours and pillars or a lightly shading tree), as it cannot cling. Alternatively, plant this creeper in groups as a ground cover, or on a bank or terraces where it can trail downwards. (1)
Culinary and Medicinal Uses
In some Native American herbal medicines, an infusion of the black eyed susan roots have been used to treat cold, dropsy, and worms in children. This mixture has also been used for sores and snake bites, while the liquid within the roots has been used as earache drops. (2) The Menominee and Potawatomi native American tribes as a diuretic as well as cooking the leaves as spring greens.
Significance to Cultural Communities
Black-eyed susans are native to Eastern Africa, and has been naturalized in other parts of the world. It is found in Cerrado vegetation of Brazil and Hawaii, along with eastern Australia and the southern USA in the states of Texas and Florida. The name 'Black-eyed Susan' is thought to have come from a character that figures in many traditional ballads and songs. In the Ballad of Black-eyed Susan by John Gay, Susan goes aboard a ship in-dock to ask the sailors, where her lover Sweet William has gone. Native Americans used the root of this plant to make a tea for a variety of treatments. They also used the yellow disk florets to create a dye to color rushes to be woven into mats. (3) Black-eyed susan is the official state flower of Maryland. At Baltimore's Preakness Stakes (horse race) the winner gets a horseshoe shaped arrangement of black-eyed susans around their neck. Black-eyed susans usually grow on roadsides throughout Maryland and most of America, and to some symbolize the American dream of opportunity for all, since they are so widespread. (4)
From the Community Voice
"All in the downs, the fleet was moored,
Banners waving in the wind.
When Black-Eyed Susan came aboard,
and eyed the burly men.
“Tell me ye sailors, tell me true
Does my Sweet William sail with you?”
Though battle call me from thy arms
Let not my pretty Susan mourn;
Though cannons roar, yet safe from harms
William shall to his Dear return.
Love turns aside the balls that round me fly
Lest precious tears should drop from Susan’s eye."
- "Black-eyed susan" John Gay
1. Smithies, Shirley. “Thunbergia alata.” Plantzafrica. January, 2007. http://www.plantzafrica.com/planttuv/thunbergalata.htm.
2. “Medicinal herbs: Black eyed susan.” Natural Medicinal Herbs. http://www.naturalmedicinalherbs.net/herbs/r/rudbeckia-hirta=black-eyed-susan.php.
3. Nuffer, Barara. “Black-eyed Susan.” New York State Conservationist. August 2007. http://www.dec.ny.gov/pubs/39317.html.
4. Allen, Ray. “The Black-Eyed Susan.” American Meadows. http://www.americanmeadows.com/about-black-eyed-susans