A brown lawn is a symptom of plant stress, signaling a lack of chlorophyll which is the pigment responsible for the grass’s green color and its ability to produce food. This discoloration shows that the grass blades are dying or that the entire plant has entered a survival mode. Since browning is not a specific diagnosis, identifying the exact cause is the necessary first step toward recovery. The correct solution depends entirely on whether the grass is merely resting, under attack, or physically damaged.
Dormancy and Drought Stress
Drought is the most common reason a lawn turns uniformly brown, forcing the grass into a protective state called dormancy. When water becomes scarce, the grass conserves resources by halting growth and sacrificing its above-ground blades. This discoloration appears across the entire lawn as the plant sends energy down to protect the crown, the base of the plant.
A simple “tug test” can help determine if the grass is dormant or dead. If you pull on a handful of brown blades and they resist, with the roots remaining anchored, the grass is likely dormant and the crown is still alive. If the grass pulls up easily like a carpet, the roots have died, and the entire plant is dead, often due to prolonged drought, which the crown can only endure for about three to four weeks in high heat. To prevent summer dormancy, turfgrass needs deep, infrequent watering, aiming for about one inch of water per week to encourage deep root growth.
Pests and Pathogens
When browning appears in distinct, non-uniform patches, a biological cause such as disease or insect infestation may be the culprit. Fungal diseases often thrive in specific conditions, like the high heat and humidity that promote Brown Patch disease, which creates large, irregular circles of tan grass that can measure up to several feet across. Dollar Spot fungus, in contrast, results in smaller, sunken patches that are typically the size of a silver dollar and often appear when the grass is low on nitrogen.
Insect pests attack the turf in different ways, leading to specific damage patterns. Grubs, the C-shaped larvae of beetles, feed on grass roots beneath the soil, which severs the plant’s connection to water and nutrients. This root damage can be confirmed if the brown turf peels back easily from the soil like a piece of sod. Chinch bugs, on the other hand, use specialized mouthparts to suck sap from the grass blades and inject a toxin, causing irregular patches that look like severe drought damage, even when the lawn is adequately watered.
Chemical and Mechanical Injuries
Sometimes, the cause of discoloration is a localized injury resulting from human activity or accidental chemical exposure. Over-application of granular fertilizer, which is rich in nitrogen salts, can draw water out of the grass roots in a process called “salt burn,” creating sharply defined brown streaks or patches. Spilled gasoline or herbicide drift from weed control products will also cause immediate, localized death that results in an unnatural, stark brown patch.
Pet urine is a common cause of browning, which is essentially a chemical burn from the high concentration of nitrogen and salts in the waste. These spots are often ringed by a patch of exceptionally dark green grass, as the diluted outer edges of the urine spot act as a nitrogen fertilizer. Mechanical injury, such as “scalping,” occurs when a lawnmower is set too low and removes too much of the grass blade at once, which exposes the vulnerable crown and leaves the turf temporarily brown and stressed.
Steps for Recovery
Once the specific cause of the brown patch is diagnosed, a targeted recovery plan can begin. For areas that are merely dormant, a return to proper, deep irrigation is usually sufficient, allowing the crown to rehydrate and push out new green blades. If soil compaction is an issue, which restricts water and nutrient flow to the roots, core aeration can be performed to remove small plugs of soil and improve air and water penetration.
If the damage is extensive, such as from insect feeding or chemical burns, the dead turf must be raked out to expose the bare soil. A soil test can help reveal any nutrient imbalances or pH issues, which should be corrected before reseeding. Overseeding or patching with new sod is necessary for dead areas, followed by a light layer of topsoil and consistent moisture to support the germination of the new seedlings. Remedial actions like adjusting the soil pH with lime or sulfur and managing thatch can improve the overall health of the lawn, making it more resistant to future stress.