Bermuda grass (Cynodon dactylon) is a warm-season perennial grass that frustrates gardeners globally. While often used for durable turf, it behaves as an invasive weed when it encroaches on garden beds. It spreads aggressively via seed, above-ground runners (stolons), and resilient underground stems (rhizomes).
This extensive network allows the grass to spread rapidly and store considerable energy, making complete eradication difficult. Even small fragments of rhizomes left in the soil can quickly regenerate into a new plant, rendering superficial weeding ineffective against established infestations. Successfully removing this tenacious grass requires patience and a sustained, multi-method approach.
Manual and Physical Eradication Methods
For gardeners avoiding chemical treatments, especially near vegetables or sensitive ornamentals, physical removal is a viable, though labor-intensive, control method. Manual control requires the meticulous removal of every piece of the subterranean root system, as the grass regrows from small rhizome fragments. Deep digging involves using a spade or fork to loosen and lift the soil, carefully sifting it to pull out all rhizomes and stolons.
The soil must be loosened to a depth of at least six inches, as rhizomes penetrate deep. All removed material should be bagged and discarded, never composted where it can re-root. This method is time-consuming and often requires repeated efforts as new shoots emerge from missed fragments. For larger, empty beds, solarization is a powerful non-chemical option that uses the sun’s heat to kill the grass and its seeds.
To solarize effectively, mow the area low, water it thoroughly, and cover it with a clear, UV-stabilized plastic sheet (typically 1.5 to 6 mil thick). The plastic edges must be sealed by burying or weighing them down to trap heat, raising the soil temperature to lethal levels. For Bermuda grass, this process must occur during the hottest part of summer for a minimum of six weeks, temporarily taking the garden bed out of use.
An alternative non-chemical approach is smothering, also known as sheet mulching or occultation, which deprives the grass of sunlight. This involves laying down thick, overlapping layers of opaque material, such as cardboard or black plastic, and covering it with mulch. Overlapping is crucial to prevent runners from finding light and growing through cracks.
Smothering is slower than solarization, often requiring the material to remain in place for six to eight months to exhaust the energy reserves stored in the rhizomes. While it kills the grass tops, the opaque material does not reach the high temperatures necessary to kill deeper rhizomes and seeds. This method suppresses the plant by starving it over time.
Targeted Herbicide Application
When physical methods are insufficient or the infestation is widespread, chemical control can be employed with careful precision, especially in an active garden environment. The choice of herbicide depends significantly on whether the garden bed contains desirable broadleaf plants. Non-selective herbicides, most commonly those containing glyphosate, will kill nearly all plants they contact, including vegetables and flowers.
Glyphosate is a systemic herbicide, absorbed by the foliage and translocated into the roots, stolons, and rhizomes, making it effective for total bed clearing. The most effective strategy involves a “kill, wait, kill” sequence because a single application rarely eradicates all deep rhizomes. The initial application is followed by a waiting period of several weeks for the grass to regrow, and then a second or third application targets the weakened new growth.
Where Bermuda grass grows among desired broadleaf plants, gardeners must use a selective post-emergent herbicide, often called a graminicide. These specialized chemicals target and kill grasses while leaving broadleaf plants unharmed. Active ingredients like fluazifop-p-butyl or sethoxydim inhibit lipid synthesis in the grass, effectively shutting down growth at the cellular level.
These selective herbicides are systemic, moving throughout the grass and accumulating in growth points and underground structures. They must be applied to actively growing grass for maximum effect. Following label instructions precisely is paramount, as is avoiding application during extreme heat or drought stress, which reduces the grass’s ability to absorb the chemical. A surfactant is often required to help the chemical penetrate the grass’s waxy leaf surface.
Long-Term Management and Recurrence Prevention
Eradicating Bermuda grass is seldom a one-time event; long-term success relies on consistent vigilance and preventative measures after initial clearance. One effective preventative measure is installing a physical root barrier around the garden perimeter, especially where it borders an infested lawn or wild area. Barriers made of metal, heavy plastic, or concrete edging should be sunk at least six to eight inches deep to block creeping rhizomes from entering the bed.
Once the garden is cleared, amend the soil to improve its health and promote the growth of desirable plants, enabling them to outcompete new Bermuda grass shoots. Since Bermuda grass thrives in full sun, planting dense ground covers or closely spaced crops that create shade can suppress its growth, as it cannot tolerate low light. The focus shifts to competition, where desired plants shade the soil surface and deny the weed necessary sunlight.
Garden maintenance plays a significant role in prevention; avoiding tilling is important because it chops the rhizomes into numerous pieces, multiplying the problem. Gardeners should rely on surface cultivation or hand-pulling instead of tilling, which spreads underground fragments. Constant monitoring is necessary, and any new shoots should be immediately spot-treated with a selective herbicide or carefully dug out before establishing a new rhizome network.
Maintaining an active layer of organic mulch, such as wood chips or shredded bark, at a depth of three to four inches will help suppress new growth from seeds or small rhizome fragments. While mulch alone will not kill established Bermuda grass, it makes hand-pulling significantly easier. The grass roots more loosely in the mulch layer, allowing the entire runner and root system to be extracted intact.