NATIVES TO KNOW
Inland Sea-oats, Chasmanthium latifolium
Compiled by Joyce Tuharsky
If you want to add native grasses to your garden, you may think you need a prairie setting with full sun. Not so with Inland sea-oats! This charming native grass thrives in partial to full shade.
Chasmanthium latifolium has several common names including Inland sea-oats, Northern sea-oats, Wild oats, Indian wood-oats, River oats, and Upland sea-oats. The common theme is “oats,” named after the plant’s graceful flat oat-like seed heads, which are attached to slender arching stalks that dangle and sway in the breeze, adding texture and motion to a garden.
Inland sea-oats are also notable for its long broadly lanceolate, leaf blades—up to 1” wide at base. They have shorter leaves that diverge from the stems at various angles, giving the plant a bamboo-like appearance. Vivid blue-green in spring and summer, the leaves turn golden in fall.
A clump-forming grass, Inland sea-oats grows 2–4 ft tall and 2–3 ft wide. It flowers in mid to late summer (July/August) and is pollinated by wind. The chevron-shaped seed heads emerge green, turn purplish bronze by late summer, and mature to a buff color in fall.
Inland sea-oats is native to central and eastern United States, north to Michigan and Wisconsin, and south to Florida and northeastern Mexico. Throughout its natural range, this plant is found in wooded areas, on shaded slopes, and along creek beds. The seed heads are eaten by birds and small mammals, and the stems and leaves are used as nesting material. It is a larval host to butterflies such as the Pepper and Salt Skipper and the Northern Pearly-Eye.
In the garden, Inland sea-oats is popular as a low-maintenance shade grass, providing interest almost year-round. It can be used as a foundation species; massed for low screening; used in mixed border plantings, naturalized areas, along streams, or on the periphery of a water garden; or planted in containers. It prefers part-shade and moist, well-drained soil; but will tolerate sunny sites and clay if moisture is adequate.
Inland sea-oats is easy to propagate by root division or seed. In fact, it re-seeds so easily that it can be considered aggressive. Trim back to the basal rosette in late winter or early spring to remove the seeds if desired. If the leaves exceed 2 feet tall by late spring and you’d like to keep it shorter, cut them in half in June.
Over time, the fibrous roots of Inland sea-oats will make a solid mat useful for soil erosion control, particularly along streams. This plant has no serious pest problems and tolerates walnut. The attractive seed stalks are used in floral arrangements.
Inland sea-oats are commonly available from seed companies/nurseries, but does have cultivated varieties. Be sure to check for its scientific name: Chasmanthium latifolium. Also, because of its wide range and variability, Inland sea-oats should be from local sources.
For more information:
Indian Sea-oats (usda.gov)
Inland Sea Oats: My Favorite Native Grass – Native Backyards
Inland sea-oats fruits photo: Chris Evans, University of Illinois, Bugwood.org
Inland sea-oats clump photo: John Ruter, University of Georgia, Bugwood.org