Helping You Become a More Successful Gardener
James H. Schutte
What a midsummer knockout! American senna's tall stature and large panicles of bright golden yellow flowers shine in the bright sun. An herbaceous perennial, this wildflower is native to prairies, old-fields and open woodlands from Ontario south to Wisconsin, Tennessee and Georgia. Fall frosts kill the plant to the roots, but the dry stems and seed pods persist into the winter before collapsing and decaying providing some visual interest.
Rising from the warm soil in mid- to late-spring, America senna quickly grows to become a tall, upright plant with fine, compound leaves. The rich green leaves alternate in a whorl on the stems. Each leaf comprises numerous oblong leaflets. In mid- to late-summer, panicles of five-petaled yellow blossoms appear along the upper stems. Bees pollinate the flowers, resulting in the production of seed pods. Hummingbird visits are also possible. The short pods turn chocolate brown and persist into fall, adding visual color and texture, though they can self-sow prolifically, so it may be wise to remove the pods before they shatter.
Easy-to-grow from seed, American senna is best grown in full sun in nearly any well-drained soil. It grows in average loam to moist sand with a neutral pH. Appreciating moist soil, it tolerates drought once established. Cut back dead stems in late fall to early winter. This senna is ideal for a tall mixed perennial border or in a meadow garden among purple coneflowers, wild bergamot and other prairie wildflowers. Over time, American senna creates a wider clump of many stems. The cloudless sulfur butterfly species lays its eggs on this perennial and the larvae consume it as their chief food source. Once heavily used in American perennial borders in the 19th century, it's rarely planted today.
American senna's leaflets are smaller than and produces more flowers compared to the Maryland senna (Senna marilandica). Both are perennials, but the Maryland senna is native to a larger, more southern range.
10 - 3
3 - 9
A3, 1a, 1b, 2a, 2b, 3a, 3b, 4, 5, 6, 7, 8, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24
Full Sun, Partial Sun
4'-5' / 1.2m - 1.5m
3'-3' / 0.9m - 0.9m
Summer, Late Summer
Northeastern United States, Mid-Atlantic United States, Southeastern United States, North-Central United States, Canada
Drought Tolerant, Average Water
Cutflower, Feature Plant, Mixed Border, Wildflower
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