Quick Answer
If parts of your lawn are turning brown while the rest stays green, the problem is usually one of six things:
- Uneven sprinkler coverage
- Underwatering
- Compacted soil
- Irrigation system problems
- Disease or pests
- Pet damage or localized stress
The key is figuring out whether the brown grass is caused by irrigation — or something else. That's what we'll help you determine.
Tools You May Need
- Screwdriver or long soil probe
- Small flags or markers
- Empty tuna cans or rain gauges
- Garden hose
- Flat shovel (optional)
Before You Start
Answer these questions first:
- Is the entire lawn brown, or only certain areas?
- Has the weather recently become much hotter?
- Did the problem appear suddenly or gradually?
- Is the affected area watered by the same sprinkler zone?
These answers alone narrow the diagnosis considerably.
The First Question Every Irrigation Technician Asks
Is the sprinkler system actually causing the problem?
Many homeowners assume brown grass means they need to water more. Sometimes that's true. Often, it isn't. Before changing your watering schedule, determine whether the irrigation system is delivering water evenly.
Step 1 — Watch the Zone Run
This is the first thing we'd do on a service call. Run the affected zone for several minutes and simply watch it.
Look for:
- Heads that don't pop up
- Heads stuck halfway
- Broken spray patterns
- Water spraying sidewalks
- Blocked spray from shrubs
- Rotors not rotating
- Dry gaps between sprinklers
Step 2 — Check for Head-to-Head Coverage
Professional systems are designed so every sprinkler throws water to the next sprinkler. This is called head-to-head coverage.
If the spray falls short, the area between heads gets far less water and turns brown first. Watch for dry strips between heads, brown circles around sprinklers, and dry corners.
The Shape of the Brown Patch Tells You a Lot
- Long strip — misaligned nozzle, blocked spray, or poor head spacing.
- Perfect circle — clogged nozzle, broken sprinkler, dog urine, or fungus.
- Dry ring around a sprinkler — the head is throwing water too far. A dual-spray nozzle or nozzle change often fixes it.
- Random irregular patches — usually disease, grubs, compaction, or localized dry spots.
Step 3 — Perform a Catch Can Test
One of the simplest ways to prove whether coverage is even.
- Place several identical containers (tuna cans work well) across the affected area.
- Run the zone for 15–20 minutes.
- Compare how much water collected in each container.
- All roughly equal → coverage is likely fine. Investigate other causes.
- Some nearly empty → uneven coverage. Investigate nozzles, pressure, blocked spray, or head spacing.
Step 4 — Check Soil Moisture
Don't rely on how the surface looks. Push a screwdriver into the green area and the brown area.
- Easier in green, hard in brown → the dry area isn't getting enough water.
- Both feel equally moist → the cause probably isn't irrigation.
Common Causes
1. Uneven sprinkler coverage
By far the most common cause. Look for misaligned heads, clogged nozzles, incorrect nozzles, heads blocked by plants, low pressure, or broken risers.
2. Compacted soil
Even if enough water reaches the area, compaction may prevent it from soaking in. Push a screwdriver into the soil — if it's hard to push after watering, aeration often helps.
3. Incorrect watering schedule
Watering every day for a few minutes encourages shallow roots. Water deeply and less frequently to encourage deeper roots. Adjust seasonally.
4. Nutrient deficiency
If irrigation looks uniform but the grass is pale or thinning throughout, consider a soil test before fertilizing. Guessing at what's missing wastes money and can damage the lawn.
5. Lawn disease
If patches expand despite proper watering, disease may be involved. Look for orange powder on shoes (rust), circular patches, or web-like growth in the morning. Take a sample to a garden center for identification.
6. Grubs and other pests
Grab the turf near the brown patch. If it lifts like loose carpet, check for white grubs underneath.
7. Dog urine
Small circular brown patches with a darker green ring outside are classic. Nitrogen burns the center and fertilizes the edge.
Common Mistakes
- Watering longer before checking whether coverage is even
- Replacing sprinkler heads without verifying nozzle or radius
- Assuming brown grass always means underwatering
- Ignoring shrubs that have started blocking spray patterns
- Fertilizing before determining whether the problem is irrigation-related