The answer to whether Bermuda grass chokes out weeds is generally yes, but this ability depends entirely on the health and density of the turf. Bermuda grass (Cynodon dactylon) is a warm-season turfgrass highly valued in the southern and transition zones of the United States for its resilience and rapid growth. This grass creates a thick, resilient turf that actively competes with and suppresses many common lawn weeds. However, this natural suppression is only successful when the grass is properly maintained and is challenged by less aggressive weed species.
The Aggressive Growth Strategy of Bermuda Grass
The remarkable ability of Bermuda grass to dominate a landscape stems from its dual-action growth system, utilizing both above-ground and below-ground runners. The plant produces stolons, which are above-ground stems that creep along the soil surface, rooting at the nodes to form new plants and rapidly spreading horizontally. Simultaneously, it develops rhizomes, which are underground stems that store energy and allow the grass to expand beneath the soil surface, forming a dense, interlocking mat.
This combined network allows the grass to quickly colonize open areas, forming a thick canopy that shades the soil. The dense coverage physically blocks sunlight from reaching the soil surface, which is necessary for the germination of many weed seeds. Bermuda grass is also noted for its potential allelopathic activity, releasing chemical compounds into the soil that inhibit the growth of competing plant species.
Weeds Bermuda Grass Successfully Outcompetes
The aggressive physical growth and dense canopy of a healthy Bermuda grass lawn prove effective against common, less vigorous weeds. Established Bermuda grass reliably suppresses annual weeds, which complete their life cycle within a single growing season. When the turf is thick, these seeds cannot receive the sunlight needed to germinate and grow.
This suppression is noticeable against shallow-rooted broadleaf weeds and many grassy annuals. Weeds that struggle beneath a thick Bermuda mat include crabgrass (once the turf is established), chickweed, and spurge. The lack of available light and intense competition for water and nutrients prevent these plants from gaining a foothold.
Limitations and Weeds That Persist
Despite its aggressive nature, Bermuda grass is not a complete weed control solution and has limitations. The grass struggles to suppress weeds that have deep root systems or aggressive reproductive structures. Weeds with deep taproots, such as dandelions, can draw nutrients and water from soil depths that Bermuda grass roots do not fully dominate.
A particularly challenging group is perennial weeds that spread via tubers or rhizomes, such as nutsedge (a sedge, not a true grass). Nutsedge’s underground tubers allow it to persist and spread even through a dense turf layer, often requiring specialized herbicides. Bermuda grass requires full sun to maintain density; shaded areas will thin out, creating bare patches where shade-tolerant weeds like ground ivy or Virginia buttonweed can thrive.
Cultural Practices for Optimal Weed Suppression
For Bermuda grass to act as an effective natural weed suppressor, it must be maintained at peak health and density through specific cultural practices. The mowing height is a primary factor, as Bermuda grass should be maintained low (typically 0.5 to 1.5 inches) to encourage the maximum lateral spread of its stolons. This low, frequent mowing creates a tighter, impenetrable turf canopy that physically prevents weed seedling emergence.
Proper fertilization, particularly nitrogen application, is necessary to fuel the aggressive growth required for dominance. Bermuda grass is a heavy feeder, requiring one to four pounds of nitrogen per 1,000 square feet annually. Primary applications should occur in late spring through mid-summer when the grass is actively growing. Watering should be deep and infrequent (about one inch per week) to encourage deep root growth, making the lawn more resilient and better able to compete with weeds for subsurface resources.