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Brown patches of dead grass on a residential lawn

Why Your Lawn Has Brown Patches (And What’s Actually Causing Them)

LAWN

Nothing ruins a nice lawn faster than waking up one morning to find random brown spots scattered across the yard. You were watering. You were mowing. Everything seemed fine. And now it looks like someone took a blowtorch to sections of your grass.

I see this all the time, and the first thing I tell people is to slow down before throwing products at the problem. Brown patches can be caused by a dozen different things, and treating for the wrong one usually makes things worse or just wastes your money.

Let me walk you through the most common culprits and how to figure out which one you’re dealing with.

It Might Just Be Thirsty

The simplest explanation is often the right one. If you’re seeing brown patches during a hot, dry stretch and you haven’t been watering much, your lawn is probably just drought-stressed.

Grass responds to drought by going dormant. It’s not dead—it’s conserving energy by shutting down above ground while keeping the roots alive below. The blades turn brown and crispy, but the plant is still there waiting for water.

Here’s a quick test: if the brown areas are random and spread throughout the yard, especially in spots that get full sun or where soil is thin, drought stress is likely. Try watering deeply a couple times a week and see if things green up within a week or two. According to Penn State’s turfgrass program, established lawns generally need about an inch of water per week, whether from rain or irrigation.

One thing to watch out for: dormant grass and dead grass look similar. The difference is that dormant grass will come back when conditions improve. Dead grass won’t. If you’re not sure, grab a handful of the brown grass and tug. If it pulls up easily with no roots attached, it’s dead. If there’s resistance and you see white roots, it’s just dormant.

Too Much Water Is Just As Bad

This one surprises people. If your lawn stays soggy, the roots can actually drown. Grass roots need oxygen, and when the soil is waterlogged, they suffocate. You’ll see yellowing first, then browning, and eventually the grass dies.

Overwatering also creates perfect conditions for fungal diseases, which I’ll get to in a minute.

If you have brown patches in low spots where water tends to collect, or if the soil feels spongy when you walk on it, you might be dealing with drainage issues or simply watering too often. Backing off on irrigation and letting the soil dry out between waterings can help. Some yards need grading work or drainage solutions to fix the underlying problem.

Fungal Diseases Are More Common Than You Think

When I see brown patches with distinct edges—especially circular or ring-shaped patterns—my first thought is fungal disease. There are several that hit lawns in Pennsylvania and similar climates, and they’re more common during humid stretches or when lawns stay wet overnight.

Brown patch is one of the most frequent offenders. It shows up as circular areas of dead-looking grass, sometimes with a darker ring around the edge. It tends to hit during warm, humid weather and often appears in lawns that were watered in the evening. The Clemson Cooperative Extension describes it as one of the most damaging turf diseases in the country.

Dollar spot is another one. It creates smaller bleached-out spots, roughly the size of a silver dollar, that can merge into larger dead areas if left unchecked. It often shows up when nitrogen is low and nights are cool with heavy dew.

Red thread looks exactly like it sounds—you’ll see pinkish-red threads on the grass blades, usually in irregularly shaped patches. It’s common in spring and fall when it’s cool and damp.

The tricky part with fungal diseases is that you usually need to identify which one you’re dealing with before treatment. Throwing a generic fungicide at the problem doesn’t always work, and improper treatment can let the disease spread. If you’re seeing distinct patterns and the patches have a weird color or texture to them, it might be worth getting a proper diagnosis from your local extension office.

Something Might Be Eating Your Lawn

If the brown patches peel up like carpet when you pull on them, you probably have grubs. These are the larvae of beetles—Japanese beetles, June bugs, European chafers—and they live underground eating grass roots. Once they’ve severed the roots, the grass dies and separates from the soil.

According to the University of Minnesota Extension, you can confirm grubs by cutting a one-foot square of sod about three inches deep and peeling it back. Count the grubs. If you find ten or more in that square foot, you’ve got a problem worth treating.

Other signs of grub damage include animals tearing up your lawn. Skunks, raccoons, and birds love to dig for grubs. If your yard suddenly looks like something’s been rooting through it at night, the grubs are probably the real issue—the animals are just taking advantage of the buffet.

There are other insects that cause brown patches too. Chinch bugs suck the juice out of grass blades and tend to concentrate in sunny, dry spots near driveways and sidewalks. Sod webworms chew grass blades at the soil line. These are harder to spot but worth considering if you’ve ruled out the other causes.

You Might Have Burned It

Fertilizer burn is real, and I see it more than I’d like. If you applied fertilizer recently and then noticed brown patches, especially in a pattern that matches your spreader path, you probably put down too much or overlapped your passes.

Nitrogen burns grass when it’s too concentrated. The lawn can’t absorb it all, and the salt content draws moisture out of the plant. The result is brown, dead grass in streaks or patches wherever the product was heaviest.

There’s not much you can do after the fact except water heavily to try to flush the excess fertilizer through the soil. In severe cases, you’ll need to reseed those areas once the soil recovers.

This also happens with other things people spill on their lawn: gasoline, motor oil, cleaning products, even dog urine in concentrated spots. If the brown patch matches the shape of a spill, that’s your answer.

The Soil Underneath Matters

Sometimes the grass itself isn’t the problem—it’s what’s below it.

Compacted soil prevents water, air, and nutrients from reaching the roots. You’ll see brown patches in high-traffic areas or spots where heavy equipment sat during construction. The fix is usually aeration, which pulls plugs of soil out and lets the ground breathe again.

Shallow soil can also cause problems. If there’s only a few inches of topsoil over rock, clay, or construction debris, grass roots can’t grow deep enough to handle stress. These spots dry out fast and brown first during any hot spell.

I’ve also seen lawns with buried debris—old concrete, lumber, you name it—that creates dead zones where grass can’t establish. If you have a persistent brown patch that never improves no matter what you do, it might be worth digging down to see what’s under there.

Figuring Out What You’re Dealing With

The hard part is that a lot of these things look similar from the surface. Brown grass is brown grass. But there are some patterns that help narrow it down.

If the patches are random and scattered, think drought, heat stress, or soil issues. If they’re circular with defined edges, think fungal disease. If they peel up like carpet, think grubs. If they follow a line or pattern, think fertilizer burn or a spill. If animals are digging, something underground is attracting them.

The time of year matters too. Fungal diseases peak during humid weather. Grub damage shows up in late summer and early fall when the larvae are largest. Drought stress hits during hot, dry stretches.

When you’re not sure, the best move is to take a close look—get on your hands and knees and really examine the grass blades, check for insects, feel the soil, tug on the roots. The answer is usually there if you look carefully enough.

When To Call It

Most brown patch problems are fixable if you catch them early and treat the actual cause. But some situations are beyond basic DIY fixes. Severe fungal infections might need professional-grade products. Major grub infestations can require proper timing and application rates to knock them out. Drainage issues might need actual construction work.

If you’ve tried the obvious fixes and the problem keeps coming back or spreading, it’s probably time to get someone out to look at it. A proper diagnosis saves money in the long run compared to guessing wrong and throwing products at something that doesn’t improve.

Your lawn wants to grow. Usually it just needs you to figure out what’s holding it back.

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