Switchgrass (Panicum virgatum) grows in damp sites between 2 and 7 feet high from U.S. Department of Agriculture plant hardiness zones 5 through 9. Switchgrass generates leaves as long as 24 inches. The grass in the wild grows in open damp prairie regions. Birds and mammals consume the leaves as well as the seeds, also using switchgrass as cover from predators, notes Kansas Wildflowers & Grasses. Cheyenne Sky is a swithgrass cultivar with blue-green leaves that change to "wine red" in early summer, according to the Missouri Botanical Garden. Growing to 36 inches tall, Cheyenne Sky does best in full sun and damp loam.
USDA zones 5 through 9 support Little Bunny, a dwarf cultivar of fountain grass (Pennisetum alopecuroides). Little Bunny grows to 18 inches high, making it suitable for your rock garden. Little Bunny has attractive flowering heads that emerge at the top of the stalks from August into October. Moudry grows to 30 inches in the same planting zones, with wet soils no problem for this cultivar. However, if you plant it in partial shade, you will have fewer flowers to admire when they bloom late in summer.
Reed grass (Calamagrostis bracytricha) generates plumes above its leaves, with the entire grass reaching 4 feet high. Hardy to USDA zone 4, reed grass is an Asian variety used to spice up wet areas near ponds and streams. A fertile and moist soil that does not become dry is a perfect place to plant Overdam, a selection of feather reed grass. The leaves grow as high as 12 inches, but the June flowers can rise another 24 inches beyond that. This vertical, clump-forming grass works well in confined areas.
Prevent soil erosion or adorn marshy spots and wet ditches with prairie cord grass (Spartina pectinata). It grows to 7 feet tall and does so well in moist soil that it has the alternate name of slough grass. Prairie cord grass grows rapidly and is a favored habitat of the colorful red-winged blackbird. Frost grass (Spodiopogon sibiricus) is an ornamental species of grass hailing from nations like China. Growing to 5 feet, it somewhat resembles bamboo. Late in the growing season, frost grass turns purplish tints.