The creeping perennial, Bermuda grass (Cynodon dactylon), spreads aggressively by above-ground stems called stolons and underground stems called rhizomes. It is a popular turf for sports fields, golf courses and parks in the South, but it is considered moderately invasive in some areas of the United States, as well as in Bermuda. Green most of the year, it tends to lose color in winter. It likes temperatures between 60 and 95 degrees Fahrenheit and is winter-hardy in U.S. Department of Agriculture plant hardiness zones 9 to 11. Blocking its spread by using landscape barriers is no small chore, but you do have various options.
When you think of barriers, you probably picture something vertical, akin to a wall. Bermuda grass barriers can be vertical with an underground component or horizontal such as with a material laid on top of the grass. Vertical barriers may be made of plastic, fabric or even concrete. Horizontal barriers are typically made of plastic, fabric or newspapers. Alternatively, a shallow trench can be dug around the Bermuda grass to contain it.
Buried fabric or plastic barriers around Bermuda grass will block its creeping stolons and rhizomes, but the barriers need to be at least 8 inches deep. Bury the barrier at an angle facing outward, so it directs the rhizomes toward the surface not down where they can go under the barrier. This solution is recommended only if you don’t have any Bermuda grass planted to begin with and you are prepared to patrol your barrier regularly for stolons or rhizomes growing over or under your barrier. You can also lay a 4-inch deep by 4-inch-wide concrete barrier to block rhizomes with bricks on top to stop the stolons, but this is expensive and the rhizomes may find their way under the concrete anyway.
Bermuda grass needs sun to grow. You can lay a horizontal barrier of plastic or landscape fabric over the perimeter of the Bermuda grass you want to control. Overlap the plastic or fabric and cover it with a mulch of chips or pine straw to give it a natural appearance, and keep it in place for six to eight weeks during the summer growing season. In another variation, mow the edge of your Bermuda grass closely, and lay six to eight sheets of newspaper over it. Wet the newspaper between sheets so they stick together, and ensure they lie lat. Cover your newspaper barrier with a mulch to give it a natural appearance.
Dig a trench 4 inches wide and 4 inches deep around the Bermuda grass. Your trench has to be nearly level or it may channel rain water and slowly erode. Another drawback is that when the grass is actively growing the aggressive rhizomes and stolons will attempt to breach the trench. So you need to trim them once a week with an edge trimmer.