Content Detail

Northern sea-oats is a grass native to the southern half of Illinois. This warm season, clumping grass has interesting oat-like seed heads that rustle easily in the wind, adding movement to the garden. It self-seeds and may spread aggressively.

This species is native to the Chicago Region according to Swink and Wilhelm’s Plants of the Chicago Region, with updates made according to current research.

  • Family (English) Grass
  • Family (botanic) Poaceae
  • Tree or plant type Grass, Perennial
  • Native locale Illinois, North America
  • Size range Large plant (more than 24 inches)
  • Light exposure Full sun (6 hrs direct light daily), Partial sun / shade (4-6 hrs light daily)
  • Hardiness zones Zone 3, Zone 4, Zone 5 (Northern Illinois), Zone 6 (City of Chicago), Zone 7, Zone 8
  • Soil preference Moist, well-drained soil
  • Tolerances Clay soil, Dry sites, Road salt, Wet sites
  • Season of interest early winter, early summer, midsummer, late summer, early fall, mid fall, late fall
  • Flower color and fragrance Other
  • Shape or form Arching, Upright

Size and form:

Northern sea-oats have an upright-arching habit and can grow three to four feet tall.

Native geographic location and habitat:

Despite the name, Northern sea oats is more readily found in the Southern part of the United States. It is common in moist sites along the edges of woodlands.

Leaf description:

Northern sea-oats has shorter leaves that diverge from stems at various angles which gives the plant more of a bamboo-like appearance. Leaves are dark green when grown in shadier sites and more yellow-green in full sun. Leaves turn golden in fall, then change to tan in fall.

Flower description:

Flowering occurs in mid to late summer, July to August. The tiny, green flowers are in flat spikelets held on a thin, arching stalk and are wind pollinated.

Fruit description:

The small fruit, caryopsis or grains, form in the flat, oat-like spikelets on a thin, arching stalk. The stalk allows the fruit to dangle and shake in the wind, adding motion to the garden. New fruit start out with a bronze color and then mature to a buff color. Seed heads are often used in dried floral arrangements.

Plant care:

Northern sea-oats grows best in partial shade, but will tolerate full sun with adequate moisture. It spreads readily by seed. This warm season grass has the most active growth in summer. It can be left standing for winter interest, although with thin stems it won’t hold up to heavy snows. Cut it down to the ground in early spring before new growth begins.

List of pests, diseases and tolerances:

No serious pest problems. This grass does self-seed readily and may lead to an excess of plants. It is tolerant of black walnut toxicity.

This plant is a cultivar of a species that is native to the Chicago Region according to Swink and Wilhelm’s Plants of the Chicago Region, with updates made according to current research. Cultivars are plants produced in cultivation by selective breeding or via vegetative propagation from wild plants identified to have desirable traits.

River Mist (Chasmanthium latifolium ‘River Mist’):

A variegated cultivar with green and white striped leaves. It will self seed like the species, seedlings will have green leaves.

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