If you need something easy to grow under trees or in a shaded corner, plant river oats. Also known as upland sea oats, river oats love a little shade, average soils, and average moisture. They are very drought-tolerant once established and will also grow in poorly drained soils. The more moisture they receive the more tolerant they are of sun.
The seed heads of river oats mature in late summer. From each arching stalk, the oat-like seed heads dangle catching the breeze like a silent wind chime. In summer they are bright green, maturing to pale brown in winter. The seed heads are often used in fresh and dried flower arrangements.
River oats form a neat clump and spread by seed. In moist soils it can be aggressive, but new clumps can be easily pulled out. Its aggressive spread can be an advantage if you want to stabilize a stream bank. River oats are best kept in check by not giving them excess water or fertilizer. They are less likely to spread aggressively in the Mid-Atlantic and north than in southern states.
In winter once the seed heads have become tattered and gray, cut the dead stalks back to the ground to make way for new spring growth. The clumps grow 2 to 4 feet tall but can be cut back by half in late spring to keep them shorter.
River oats' bamboo-like leaves are an attractive blue-green shade that mixes well with other plants. Since the seed heads do not form until fall, try planting them among spring and summer flowering plants such as coral bells or woodland phlox. For an attractive fall-blooming combination plant them with wood asters or 'Golden Fleece' goldenrod. River oats can also be used to fill in among upright shrubs like fothergilla or chokeberry.
River oats grow along stream banks and rich woods from Pennsylvania south to Florida and west to Arizona. Several species of butterfly caterpillars feed on the leaves, and small mammals and song birds eat the seed heads.