Wild senna an easy-to-grow, low-maintenance native plant for home gardens

Editor’s note: Once a month, OSU Extension Master Gardener volunteers in Franklin County profile a plant that occurs naturally in Central Ohio.

Senna (or Cassia) hebecarpa, commonly known as wild senna, is a striking plant with bright green foliage and buttery yellow blooms in July and August. It’s a member of the Fabaceae (pea) family. This beautiful herbaceous plant can be found naturally in meadows, near rivers, savannahs and roadsides, but its numbers are declining due to modern development.

Wild senna can grow 3-6 feet tall and 3-4 feet wide. It has a horizontal root system, making it resistant to wind. In a home garden, it’s an excellent native option behind smaller perennials or used as a hedgerow.

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Wild senna is largely unbranched, with a central light green stem adorned with medium green, compound, evenly pinnate leaves that contain 5-10 pairs of smooth, oblong-shaped leaflets. At the base of each leaf is a small extrafloral nectary that attracts insects such as ants, ladybird beetles and flies, which are thought to defend the plant against other insect invaders that may destroy foliage. Despite these insect army guards, wild senna is a host plant for the cloudless sulphur butterfly, whose caterpillars do consume some foliage and flowers.

The showy yellow flowers develop in clusters and start to lighten toward white as they mature. The flowers contain no nectar but do offer highly nutritious pollen, which is a favorite among bumble bees and sweat bees. The seed pods are flat and about 4 inches long. They turn chocolate-brown in late autumn and rustle lightly in cool winds bringing winter interest to landscapes. The seed pods are enjoyed by larger birds like bobwhite quails and wild turkeys.

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Native Americans used the root of the plant to treat high fevers, pneumonia, and as a worm remedy. The leaves and seeds are used in modern medicine as a laxative and can be found on pharmacy shelves today.

Wild senna is a hardy, low-maintenance, beautiful addition to any home garden, benefits a variety of wildlife and has year-round interest.

Growing requirements

Hardiness zones: 4a-9b

Sun: full sun to partial shade

Water: medium-moist, tolerates periodic flooding, drought-tolerant once established

Soil: Fertile loam preferred, but tolerates sand, rocks and clay

Maintenance: Can cut back mature seed heads in autumn to prevent spread

Propagation: Easy to grow by seed or splitting plant rhizome clump in late fall or early spring

Pests and disease: no significant insect problems, deer-resistant