The appearance of brown grass signals that the turf is experiencing a form of environmental, biological, or physical stress. This discoloration is not a disease in itself but rather a symptom indicating the grass plants are reacting to adverse conditions. Healthy turf maintains its green color through the process of photosynthesis, and browning is the visible result when this process is severely compromised. Correctly identifying the underlying cause of the browning is the first step toward implementing an effective recovery strategy for the lawn.
Seasonal Stress and Dormancy
One of the most frequent causes of widespread lawn browning is a natural protective mechanism called dormancy. When conditions become unfavorable, typically due to prolonged heat or lack of water, grass plants halt active growth to conserve energy, resulting in a uniform golden-brown color. This state is a survival response, meaning the crown of the plant remains alive, awaiting the return of favorable moisture or temperatures. Cool-season grasses often enter summer dormancy to escape high temperatures and drought, while warm-season varieties may enter dormancy during the winter months to survive the cold.
Distinguishing between dormant and dead grass uses the “tug test.” Gently grasp a handful of brown grass blades and give them a light tug. If the grass is merely dormant, it will resist the pull, remaining firmly rooted because the root system is still intact and viable. Conversely, if the grass pulls out easily with little to no resistance, the root system has failed, and the plants are likely dead, requiring replacement. Further examination of the crown can confirm this finding. A white or creamy crown indicates a living, dormant plant, while a brown, brittle crown signifies turf death.
Insect Pests as Culprits
When brown patches appear irregularly, the damage may be due to insect pests. Two common culprits are grubs and chinch bugs, each causing distinct symptoms that aid in proper identification.
Grubs
Grubs are the larval stage of various beetles, and they cause destruction by feeding voraciously on the grass roots. This root-severing action detaches the turf from the soil, leading to irregular brown patches that can be easily pulled back like loose carpet. A grub-infested lawn may also feel noticeably spongy when walked upon.
Chinch Bugs
Chinch bugs cause damage by feeding on the grass blades above ground. These small insects use piercing-sucking mouthparts to extract fluids and inject a toxin, disrupting the plant’s ability to transport water. Chinch bug damage appears as irregular yellow or brown patches resembling drought stress, but the turf fails to recover even with consistent watering. Unlike grub damage, chinch bug-damaged grass does not pull up easily because their feeding does not affect the roots. They often concentrate in the hottest, sunniest areas, such as near sidewalks and driveways.
Correct identification is necessary for treatment: grubs require a soil-penetrating insecticide, while chinch bugs are treated with a topical application.
Fungal Infections and Turf Diseases
Brown grass appearing in distinct, patterned spots often suggests a fungal pathogen. Fungal infections are frequently triggered by high humidity, poor air circulation, or extended periods of leaf wetness.
Brown Patch
Brown Patch creates roughly circular brown areas that can range from a few inches to several feet in diameter. It typically affects the grass blades and is most active when air temperatures exceed 80°F combined with high humidity. In some instances, a darker, smoky-gray border or “smoke ring” may be visible around the edge of the patch, particularly in the early morning.
Dollar Spot
Dollar Spot is characterized by small, sunken spots the size of a silver dollar, usually two to six inches across. This affliction favors moderate temperatures, specifically between 60°F and 80°F, and is often exacerbated by low nitrogen levels in the soil. The damaged leaf blades may exhibit small lesions, and the patches can coalesce into larger, irregular areas.
Proper management involves avoiding late-day watering to minimize leaf wetness and ensuring the turf has adequate nitrogen nutrition.
Improper Maintenance and Chemical Burns
Improper maintenance and chemical reactions can result in brown grass, often presenting as distinct spots or patterns.
Maintenance Errors
Scalping, the practice of mowing the turf too short, removes an excessive amount of the grass blade, stressing the plant and leaving it vulnerable to browning, especially in hot weather. Similarly, the over-application of granular fertilizer can lead to chemical burn, as the high concentration of soluble salts draws moisture out of the grass plants. This results in localized browning that mirrors the application pattern.
Pet Urine Damage
Pet urine contains a high concentration of nitrogen compounds, acting like a concentrated fertilizer spill. This chemical overdose causes the grass in the center of the spot to burn and die. The surrounding area often exhibits a ring of unusually dark, lush green growth, known as the “halo” effect. This occurs because the nitrogen concentration is diluted at the perimeter, providing a fertilizing benefit to the adjacent turf. To mitigate damage, immediately and thoroughly water the area after the pet urinates to dilute the nitrogen.