Coastal Processes FAQ - Most of the grass growing on the dunes is brown in winter. Is it dead?

Each season brings a different look to Delaware's beaches and dunes. The beach may be lower and narrower in the winter than the summer, and quite often winter dunes may be cut back by wave erosion. Dune grass similarly goes through a change every winter with a period of dormancy. During winter months, many plants go into a natural dormancy, or rest period. Plant growth slows, or sometimes is halted completely. This is why the dune grass looks brown this time of year.

While the above ground portion of the plant (leaves and stems) are no longer “living,” the roots are still alive but may be less active. It's interesting to notice that even though the grass leaves and stems are brown, they are still effective in trapping wind-blown sand. Depending on springtime temperatures this year, you'll probably be able to observe new green shoots growing up at the base of each brown clump of grass by the middle of April.

The beach grass that grows on Delaware's dunes is called “Cape” American beachgrass, and its scientific name is Ammophila breviligulata. American beachgrass is native to the mid-Atlantic coast, and is the best species known for stabilizing the sand dunes in this area. Once established, it spreads by underground stems to form a dense vegetative cover. The foliage decreases the wind velocity near the dune surface, and sand is deposited in the vegetation. As the sand continues to accumulate, the grass grows up through it, maintaining a protective cover.

The best time to plant American beachgrass is from October 15 to April 1 (during the dormancy period). Good survival can be expected from planting any time during this period when the soil is not frozen. Summer plantings are not recommended. On the other hand, if the winter storm season is severe, high tides and waves may erode dunes and newly planted dune grass.