A lawn turning brown is one of the most common problems for homeowners. This discoloration is a symptom of a plant’s physical response to environmental stress, cultural mistakes, or biological threats. Identifying the root cause is the necessary first step, as the correct solution for a fungus differs completely from the treatment for a lack of water.
Dormancy Versus Death: Identifying the State of Brown Grass
Dormancy is a protective state where the grass shuts down growth to conserve energy when faced with adverse conditions like heat or drought. The brown blades are the plant sacrificing its leaves while keeping the crown and root system alive. If the brown areas are uniform across the entire lawn, the discoloration is likely a widespread dormancy response.
You can perform a simple “tug test” to confirm the grass’s state. Dormant grass will resist being pulled from the soil because its roots are still firmly anchored and alive. In contrast, dead grass is characterized by permanent cellular failure. When pulled, dead grass will come out easily, often in clumps, because the root system has failed and is no longer tethered to the soil. A watering test can also differentiate the two; dormant grass will begin to show a green tint at the base after a few days of consistent watering, while dead grass will remain brittle and unchanged.
Environmental and Cultural Stressors
The most frequent causes of brown grass are non-living, or abiotic, factors related to climate and human lawn care practices. Drought and improper watering cause the grass blades to wilt, shifting the color from green to a dull gray or bluish-gray tint. In a drought-stressed lawn, footprints often remain visible because the dehydrated grass lacks the pressure needed to spring back upright.
Extreme heat stress damages the grass’s ability to photosynthesize and can cause browning even when sufficient water is present. When temperatures exceed 85 degrees Fahrenheit, the plant redirects energy away from growth, and its root system can be damaged, making it vulnerable to further decline. This is why cool-season grasses are often the first to brown during the summer.
Another major cause of localized browning is fertilizer burn, which is chemical damage from over-application. Fertilizers contain mineral salts, and an excessive concentration of these salts draws moisture out of the grass roots and leaves through a process called reverse osmosis. This moisture loss causes the blades to rapidly dry out, resulting in scorched patches or visible brown streaks where the application overlapped.
Cultural practices like mowing too short, known as scalping, also lead to browning. Scalping removes too much of the photosynthetic tissue, exposing the pale, non-pigmented stem tissue at the base of the plant. This weakens the grass and makes it highly susceptible to heat and water loss. Additionally, soil compaction, often caused by heavy foot traffic, restricts the flow of air, water, and nutrients to the roots, leading to binned grass in high-traffic areas.
Biological Causes: Pests and Fungal Diseases
Biological factors often cause distinct patterns of browning, making them easier to diagnose than widespread environmental causes. Fungal diseases thrive in specific moisture and temperature ranges, creating predictable visual cues.
Dollar Spot fungus forms small, circular, silver-dollar-sized patches of straw-colored grass, often favored by low nitrogen levels and prolonged leaf wetness. In contrast, Brown Patch disease creates larger, irregular circular areas that can span several feet in diameter. These areas sometimes exhibit a darker, grayish border, referred to as a “smoke ring,” in the early morning dew. This fungus becomes active during periods of high humidity and warm temperatures.
Rust is a common fungus, identified by the orange or reddish-brown powdery spores that rub off the blades. This condition is often a sign of insufficient nitrogen and poor air circulation.
Insect pests attack the grass in two primary ways: feeding on the roots or the blades. White grubs, the larvae of beetles, feed on the root system, causing irregular patches of grass that can be lifted easily like a loose carpet because the roots have been severed. Chinch bugs use piercing-sucking mouthparts to extract sap from the grass blades and inject a toxic substance that blocks water flow. This feeding causes the grass to turn yellow and then brown in irregular patches that closely mimic drought stress but do not recover with watering.
Action Plan for Lawn Recovery
Once the specific cause of the browning has been identified and mitigated, a structured recovery plan can be implemented. For grass that was merely dormant due to drought, the most effective step is deep, infrequent watering. Aim to apply about 1 to 1.5 inches of water per week in the early morning. This approach encourages the root system to grow deeper, establishing greater resilience against future stress.
If soil compaction was the underlying issue, core aeration should be performed to pull small plugs of soil from the lawn. This immediately improves air and water penetration to the root zone. Excessive thatch, which can harbor pests and block water, should be physically removed through dethatching. For patches where the grass has definitively died, overseeding is necessary, which involves spreading new grass seed over the affected areas.
Fertilization should be handled with care, especially after dormancy or stress. Wait until the grass shows initial signs of greening before applying a light, controlled-release fertilizer. This provides necessary nutrients for regrowth without risking further damage from high salt concentrations.