Bermuda grass (Cynodon dactylon) is a warm-season perennial grass known for its rapid growth and resilience, making it highly challenging to control once established. Its invasiveness stems from a dual-pronged spreading mechanism that allows it to quickly colonize new territory. Successfully stopping its spread requires a combination of physical, chemical, and cultural management strategies. This comprehensive approach is necessary because the plant can regenerate from even small fragments. The following strategies provide actionable methods to contain and eliminate this pervasive turfgrass.
Understanding Bermuda Grass’s Aggressive Growth
The difficulty in controlling Bermuda grass arises from its two distinct methods of vegetative reproduction. Above-ground, it spreads rapidly using horizontal stems called stolons, which creep along the soil surface and root down at their nodes to form new plants. This allows the grass to quickly colonize open ground and low barriers.
The plant also utilizes underground stems, or rhizomes, which function as energy storage organs and a secondary spreading network. These rhizomes can penetrate deep into the soil, with most of the root mass residing in the top six inches. The deep root system grants it drought tolerance and allows it to survive extreme conditions and mechanical removal.
Because the rhizomes contain stored energy, the grass can regenerate even after the top growth has been killed. Any small, surviving fragment of a rhizome or stolon can quickly sprout a new plant, underscoring the need for persistent, multi-year control efforts.
Establishing Physical Barriers and Containment
Physical barriers are an effective, non-chemical method for preventing the lateral movement of Bermuda grass into adjacent garden beds or lawns. The goal of a barrier is to block the spread of both the above-ground stolons and the underground rhizomes.
The barrier material, such as heavy-duty plastic, metal, or concrete edging, must be installed to a specific depth to be effective. It should penetrate the soil at least six to eight inches deep to create a physical block against the horizontal rhizomes in the upper soil layer. The barrier must also extend two to four inches above the soil line to prevent stolons from creeping over the top edge and rooting.
Creating a trench barrier and lining it with commercial-grade, non-woven landscape fabric is another containment method for garden beds. This fabric is thicker and more durable than lightweight weed barriers and must be completely sealed at the edges to prevent rhizomes from growing underneath or around it. In non-turf areas, a deep layer of mulch applied over the fabric helps to further block sunlight and suppress any crossing stolons.
Chemical Elimination Techniques
Chemical control is often necessary for complete elimination, especially when Bermuda grass has heavily invaded a desirable turf area. These techniques are categorized based on whether they kill all plants (non-selective) or only the target grass (selective).
Non-selective control, typically using a product containing glyphosate, is the most direct way to eliminate Bermuda grass in bare ground or before a lawn renovation. This approach requires two or more applications, spaced three to four weeks apart, to exhaust the plant’s energy reserves in the rhizomes. For the herbicide to be absorbed effectively, the grass must be actively growing and not stressed by drought or heat, often meaning application in late spring or late summer.
Selective herbicides are used when Bermuda grass has invaded a cool-season lawn, such as tall fescue or Kentucky bluegrass. Products containing active ingredients like topramezone (Pylex), fluazifop (Ornamec), or fenoxaprop (Acclaim) are designed to target the warm-season Bermuda grass while minimizing harm to the desirable cool-season turf. Control is achieved through sequential applications, often three or more rounds every three weeks, usually starting in late summer or fall when the Bermuda grass is actively storing energy. These specialized treatments require consistent application over one or more growing seasons to achieve satisfactory control.
Cultural Practices to Discourage Spread
Long-term management involves adjusting the environment to favor desirable plants and make conditions less hospitable for Bermuda grass. This warm-season grass requires full sun to thrive and is intolerant of shade.
One effective cultural control in a cool-season lawn is to increase the mowing height to four inches or higher. The taller canopy of the desirable grass creates a dense, shaded environment that suppresses the lower-growing Bermuda grass, limiting its spread. Maintaining a healthy, dense stand of turf makes it harder for the invader to establish itself.
Adjustments to irrigation and fertilization schedules also tilt the competitive balance. Since Bermuda grass thrives in summer heat, avoiding fertilization of cool-season turf during the hottest months prevents feeding the invasive grass. Watering deeply and infrequently encourages the desirable turf to develop deeper roots, which is preferred over shallow, frequent watering that favors Bermuda grass.