Native sea-side grasses are one of the best choices for growing in a coastal garden. Naturally salt-tolerant, these grasses are suited to climates that would damage more tender grasses. Sea grasses can also be grown in inland gardens, as long as their individual needs for light, soil conditions and water are still met.
Northern Sea Oats (Chasmanthium latifolium) are one of the most commonly recommended coastal grasses. This species is hardy in U.S. Department of Agriculture plant hardiness zones 3 through 9. Partial shade is the best lighting condition for sea oats, and they prefer fertile, well-drained soil that stays moist. Sea oats grow 2 to 3 feet tall, and flower from June to September. The flowers form seed heads that turn bronze colored and last all winter. Due to its spreading roots and prolific seeds, sea oats can become invasive.
Cordgrasses (Spartina spp) are native to wet, salty locations. Sand cordgrass (Spartina bakeri) grows naturally on beaches and near inland lakes, and is hardy in USDA zones 8 through 11. It grows 3 to 4 feet tall. Prairie cordgrass (Spartina pectinata) grows 5 to 6 feet tall. It is native to dry soil as well as marshes and floodplains, and is hardy in USDA zones 4 through 9. Both cordgrasses grow best in full sun. They are not picky about soil conditions, and can tolerate either wet or dry moisture levels. They spread aggressively, and may become invasive.
Beach grasses (Ammophila spp.) grow best in well-drained, sandy locations. As coastal grasses, they are also tolerant of salt spray. American beach grass (Ammophila breviligulata) is useful for erosion control, particularly on sand dunes or sandy garden slopes. It is an east-coast native that is hardy in USDA zones 5 through 10. American beach grass grows 2 to 3 feet tall, and prefers full sun or filtered sunlight. It needs well-drained soil, but is not picky about moisture levels. This grass should not be transplanted in the summer.
Another salt-tolerant grass species that grows well near the sea are the reed grasses (Calamagrostis spp). Reedgrass (Calamagrostis arundinacea) and feather reedgrass (Calamagrostis acutiflora "Karl Foerster") are both hardy in USDA zones 5 through 9. They are not invasive, but will spread to large sizes. At 5 to 7 feet tall, they make nice windbreaks that bear pink or purple flower plumes in the summer. The grasses will grow tallest when planted in wet soil, but can grow in heavier, dryer soils as well if watered regularly. They prefer full sun to part shade.