Spartina alterniflora (Smooth Cordgrass)

A true coastal ecosystem engineer, smooth cordgrass's dense rhizome system binds coastal mud while its sturdy stems slow wave action and trap sediment, actively raising marsh elevation over time - and its documented role as an important food source for West Indian manatees and snow geese underscores its outsized ecological reach.

Species Overview

Spartina alterniflora, or smooth cordgrass, is the dominant grass species of tidal salt marshes and beaches along the Atlantic and Gulf coasts, forming dense rhizomatous colonies that eventually merge into extensive meadows. Stiffly erect, hollow stems reach 3 to 8 feet, with densely packed tan flower clusters appearing in summer and fall.

Application

• Salt marsh and coastal shoreline restoration - foundational marsh-building species
• Erosion control on canal banks and tidal shorelines
• Wildlife habitat - confirmed food source for West Indian manatees, snow geese, and fish/shellfish nurseries
• Land reclamation projects via sediment trapping and elevation building

Growing Conditions / Specification Data

• Light: Full Sun
• Soil/Moisture Tolerance: Wet, brackish to saline soils; adaptable from coarse sands to clays and mucks
• Plant Type: Graminoid
• Mature Height: 4-8 ft.
• Fall Color: Insignificant/None
• Wetland Indicator Status: NI (No Indicator) - see flags
• Native Range: Northeast/Mid-Atlantic (full list)
• Pollinator Value: None significant - wind-pollinated salt marsh grass, no meaningful nectar or pollen resource.
• Hydrology: Moist-Wet
• Root Depth: Deep (24-36 in.)
• Growth Rate: Rapid
• Drought Tolerance: Low
• Deer Resistance: Yes (Rarely Damaged)
• Shade Tolerance: Intolerant
• Salinity Tolerance: High - 8-33 ppt ideal establishment/growth range, tolerant to ~60 ppt (USDA NRCS Plant Guide; peer-reviewed growth studies)
• Flood Tolerance: High - The dominant grass of the regularly-flooded low salt marsh zone, consistent with this species' already-extensively-confirmed salinity and tidal inundation tolerance from earlier work.
• Growth Habit: Spreading - rhizomatous
• USDA Hardiness Zones: 4-9

Planting Guidance

• IMPORTANT: while native and ecologically foundational along the Atlantic and Gulf coasts, this species has been introduced to the West Coast and internationally, where it has become an invasive threat to native coastal plant communities - site only within its native East/Gulf Coast range. Establishes poorly under freshwater conditions; best planted at the mean high tide line in brackish to saline soils.