Bermuda grass (Cynodon dactylon) is a warm-season perennial turfgrass valued for its durability and resilience. It is an aggressive, sod-forming species with a vigorous growth habit. Understanding how it spreads is paramount for any homeowner, whether establishing a thick lawn or eliminating an invasive weed. The traits that make it a desirable turf also cause its notoriety as a difficult-to-control invader.
The Dual Mechanism of Spread
The ability of Bermuda grass to rapidly colonize an area is due to two distinct vegetative structures. Above ground, it produces strong, flat runners called stolons, which creep along the soil surface. These stolons have nodes that root into the soil, producing new shoots.
Below the soil, the plant develops an extensive network of underground stems known as rhizomes. These rhizomes act as a vast energy reserve, enabling the plant to survive periods of drought or dormancy. This dual system makes the grass extremely difficult to eradicate, as rhizomes can survive even if the above-ground material is destroyed.
While vegetative reproduction is the dominant method of spread, the plant also reproduces through seed production. Seed dispersal remains a means of colonizing new areas or re-establishing after a disturbance.
Encouraging Rapid Coverage
To establish a dense Bermuda lawn quickly, cultural practices maximize its spreading potential. Promoting lateral growth requires maintaining a consistently low mowing height (0.5 to 1.5 inches) to encourage the prostrate growth habit. Frequent mowing at this range allocates energy to horizontal expansion.
Bermuda grass has high nitrogen requirements, and providing a regular supply is essential for rapid coverage. During the establishment year, a rate of 1 to 1.5 pounds of nitrogen per 1,000 square feet monthly is recommended throughout the growing season.
Watering techniques also influence colonization speed. Frequent, light irrigation is necessary until the grass is well-sprouted. Once established, reduce the frequency of watering while increasing the amount applied to encourage deeper root growth and ensure maximum coverage.
Strategies for Containment and Removal
Controlling or removing Bermuda grass requires a persistent, multi-pronged approach. Mechanical removal necessitates digging out the entire plant, ensuring all fragments of stolons and rhizomes are extracted. Avoid chopping the stems, as each small piece can sprout into a new plant, spreading the infestation.
Non-Chemical Methods
For larger areas, non-chemical methods like soil solarization are effective during periods of high solar radiation, such as mid-summer. This involves mowing closely, watering the area, and covering it with clear, UV-protected plastic sheeting for six to eight weeks. This heats the soil to temperatures lethal to the plant material and seeds.
Physical barriers, such as deep edging or trenches, can also be installed along the perimeter of garden beds. These prevent the stolons and rhizomes from creeping into the cultivated space.
Chemical Control
Chemical control often involves non-selective systemic herbicides, such as those containing glyphosate. These are absorbed by the foliage and translocated down to the roots and rhizomes. For maximum effectiveness, apply the herbicide when the grass is actively growing and storing carbohydrates, typically in late summer. Multiple applications are often needed because the extensive energy reserves in the rhizomes allow the grass to recover from initial treatments.