Brown patches in an otherwise green lawn are one of the most common — and most misdiagnosed — lawn problems homeowners face. The fix depends entirely on the cause, and applying the wrong treatment wastes time and money while the real problem continues to spread. This guide covers the seven most common causes of brown patches and gives you a clear path to fixing each one.

How to Diagnose Brown Patches: Start With the Pattern

Before treating anything, observe the pattern of the damage. Shape, size, location, and edge definition tell you a lot about what’s causing the problem.

• Irregular patches with defined edges and a lighter center: Fungal disease
• Circular patches 6–24 inches, bright green ring around the edge: Dog urine or nitrogen burn
• Irregular, spongy brown areas: Grub damage (sod lifts like a carpet)
• Even browning across the lawn: Drought or heat stress
• Stripes or geometric patterns: Irrigation problem or mower scalping
• Thin, spreading brown areas near trees or shade: Insufficient light

Cause 1: Fungal Disease (Brown Patch, Dollar Spot)

Fungal diseases are the most common cause of irregular brown patches with defined edges. Brown patch (Rhizoctonia solani) affects most grass types but is especially destructive to tall fescue and ryegrass in hot, humid conditions. Dollar spot creates silver-dollar-sized bleached patches scattered across the lawn.

How to Fix It

Apply a lawn fungicide labeled for the specific disease. Avoid watering at night — fungal diseases thrive in persistently moist conditions. Water deeply in the morning so blades dry before evening. Improve air circulation through aeration. Avoid over-fertilizing with nitrogen, which promotes lush growth that’s more susceptible to fungal attack.

Cause 2: Dog Urine

Dog urine creates circular brown spots 4–12 inches in diameter, often surrounded by a dark green ring (caused by nitrogen in the urine at lower concentrations). The brown center is nitrogen burn at high concentration.

How to Fix It

Flush the area immediately with water if you catch it fresh. For existing damage, water the area deeply to dilute salts in the soil, then overseed once the brown area is fully dead. There’s no product that neutralizes dog urine in the soil effectively — flushing and overseeding is the reliable fix.

Cause 3: Grub Damage

Grubs (larvae of Japanese beetles and other beetles) eat grass roots just below the soil surface. The lawn turns brown in irregular patches and feels spongy underfoot. A definitive test: grab the sod and pull up. If it lifts like a carpet with no roots holding it down, grubs are the cause. You may find white C-shaped larvae in the soil underneath.

How to Fix It

Apply a grub control product containing imidacloprid or chlorantraniliprole. Time matters: apply preventive grub control in early summer before eggs hatch (June–July). Curative grub control (carbaryl or trichlorfon) works later in the season but is less effective. After treating, water thoroughly to move the product into the soil. Overseed damaged areas once grubs are controlled.

Cause 4: Drought and Heat Stress

When grass doesn’t receive enough water during hot, dry periods, it goes dormant and turns brown evenly across the lawn. Unlike disease damage, drought stress is usually uniform and not patchy. Footprints remain visible for several minutes after walking across the lawn — a classic sign of water stress.

How to Fix It

Resume regular, deep watering (1 inch per week, including rainfall). Most lawns recover from drought dormancy within 2–3 weeks of consistent watering. Raise your mower height — taller grass shades the soil and reduces water loss. If drought stress is recurring, consider overseeding with drought-tolerant grass varieties.

Cause 5: Irrigation Problems

Dry patches in geometric or striped patterns almost always point to irrigation issues: a broken sprinkler head, a misaligned nozzle, or a clogged emitter that’s leaving part of the lawn dry. Run each zone manually and walk the area to check coverage. Broken heads are the most common culprit in hot weather.

How to Fix It

Repair or replace damaged sprinkler heads. Adjust nozzle direction and arc. Check for clogged drip emitters in zones with drip irrigation. After repairs, check overlap to make sure there are no gaps in coverage. Overseed any areas that suffered extended drought from the irrigation gap.

After the Fix: Reseeding Brown Patches

Once the underlying cause is addressed, most brown patches need overseeding to fully recover. Rake out dead grass, loosen the top ½ inch of soil with a hand cultivator, broadcast grass seed at the full seeding rate for your grass type, and keep the area consistently moist for 2–3 weeks. Match seed to your existing lawn for the best visual result.

For a full walkthrough of the reseeding process, see our complete overseeding guide. For ongoing lawn health maintenance, check our aeration guide — regular aeration prevents the compaction and poor drainage that make lawns susceptible to disease and drought stress.

Get a Free Lawn Care Quote

If you’re dealing with widespread brown patch damage or recurring fungal disease, a professional assessment can identify the exact cause and recommend targeted treatment. Get connected with local lawn care experts for a free, no-obligation quote.