Bermuda grass (Cynodon dactylon) is a popular warm-season turfgrass known for its resilience in hot climates. While it creates a dense, attractive lawn, it is highly sensitive to environmental and cultural stressors, with browning being the most common symptom of decline. This discoloration indicates the grass is under stress from seasonal changes, improper care, or biological threats. Understanding the root cause is the first step toward restoring the lawn’s vibrant green appearance.
Seasonal Shifts and Natural Dormancy
The most common reason for Bermuda grass turning brown is its natural cycle of dormancy. Winter dormancy occurs when soil temperatures consistently drop below 55 to 60 degrees Fahrenheit, causing the grass to halt growth and lose its green pigment to conserve energy. The lawn takes on a uniform tan or straw color. The grass resumes active growth when the soil temperature, measured at a four-inch depth, stabilizes around 65 degrees Fahrenheit. Summer dormancy is triggered by extreme, prolonged heat combined with severe drought. Although Bermuda grass is drought-tolerant, it will voluntarily shut down and turn brown when moisture is insufficient, protecting its crown and root system until water returns.
Improper Maintenance and Environmental Factors
Many instances of browning relate directly to cultural practices. Watering issues are a frequent culprit, as both too little and too much water can induce brown patches. Underwatering causes the grass blades to wilt, turn grayish-green, and eventually become straw-colored as the plant enters dormancy. Overwatering is also damaging because it suffocates the roots by displacing oxygen in the soil, leading to root rot and fungal growth. Bermuda grass requires about one to one-and-a-half inches of water per week, applied deeply and infrequently. Deep watering encourages roots to grow downward, making the plant more resilient to dry spells.
Mowing practices also play a significant role. Cutting the grass too short removes too much leaf tissue. Removing more than one-third of the blade height in a single session exposes the brown stem material underneath, causing temporary discoloration and weakening the plant. Maintaining a consistent height and ensuring sharp mower blades prevents this stress.
Soil compaction, often caused by heavy foot traffic or machinery, is another environmental factor that leads to localized browning. When soil particles are pressed together, they restrict the movement of air and water to the root zone. This lack of oxygen and moisture results in thin, stressed turf that appears brown in those specific areas. Aerating the lawn helps alleviate compaction by creating channels for air and water to penetrate the soil surface.
Identifying Insect Pests and Turf Diseases
Insects and fungal diseases cause distinct patterns of browning that require targeted treatment. Grub worms feed directly on the grass roots, severing the connection between the blades and the soil. This damage manifests as irregular brown patches that feel spongy underfoot. A simple “pull test” can confirm their presence; if the affected turf lifts easily like loose carpet, grubs are likely the cause.
Chinch bugs suck fluids from the grass blades, injecting a toxin that causes the grass to turn yellow and then brown. Their damage appears in irregular, expanding patches, often found in the hottest, driest, and sunniest areas of the lawn, particularly near concrete or pavement. Unlike fungal issues, chinch bug damage does not resolve with increased watering.
Fungal diseases also create brown spots. Dollar Spot creates small, circular patches of tan or straw-colored grass, which can merge into larger irregular areas. Closer inspection of the individual grass blades reveals distinct, bleached lesions that often have a reddish-brown border.
Brown Patch creates larger, circular or irregular brown patches that can range from a few inches to several feet in diameter. This fungus is promoted by high humidity, prolonged leaf wetness, and warm temperatures, causing the grass blades to rot at the base near the soil surface. Proper watering in the early morning and ensuring good air circulation help minimize conditions favorable for these pathogens.
Chemical and Nutritional Imbalances
Incorrect usage of lawn care products can lead to browning. Fertilizer burn occurs when an excessive amount of fertilizer, particularly those high in nitrogen salts, is applied to the turf. The high concentration of salts draws moisture out of the grass blades, resulting in yellow or brown streaking where the spreader overlapped. To remediate this issue, the affected area should be flushed immediately with a large volume of water to dilute and wash the excess salts deeper into the soil.
Herbicide damage often results from product drift or accidental overspray onto the lawn itself. Herbicides intended for flower beds or weeds can cause browning or distorted growth patterns if they drift onto the turf. The pattern of the injury, such as a distinct border or an area far from the application site, helps diagnose drift as the cause.
Soil pH imbalances affect the plant’s ability to absorb nutrients. Bermuda grass prefers a slightly acidic to neutral pH range for optimal nutrient uptake. If the soil is too acidic or too alkaline, nutrients like iron and nitrogen become unavailable to the roots, leading to deficiencies. A soil test can identify this issue, allowing for the correct application of amendments to adjust the pH and restore the grass’s ability to feed itself.