Why Does My Lawn Have Brown Patches? Dig One Up First

Lifting the edge of a brown patch tells you more than any photo guide: roots that hold, roots that lift, and grubs underneath mean three different causes.

By Zakaria October 6, 2026 3 min read Save to Pinterest

A large circular patch of straw-coloured dead turf in an otherwise green lawn, with a mower stripe running through it — Photo: Plant pests and diseases, CC0, via Flickr

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Do not diagnose a brown patch from the top. Crouch down, take hold of the edge of the dead grass and pull. What happens next splits the causes into three groups before you have looked at a single photo guide.

The three tests, in order

This table answers the question on its own

Test	Result	Cause
Pull the edge	Peels away, no roots	Grubs
Screwdriver into the soil	Will not go in; soil dry	Drought / dry spot
Screwdriver into the soil	Goes in; soil wet	Disease or compaction
Look at the outline	Circle with a darker ring	Dog urine
Look at the outline	Straight strips	Mower

A long screwdriver is the best lawn diagnostic tool you own

Push it into healthy turf, then into the patch. Resistance tells you about compaction, and the soil that comes out tells you about moisture — both in about five seconds.

Grubs

Pale C-shaped larvae in the top few centimetres, and turf you can roll back. A rough working threshold is more than five to ten per square foot before you treat — a few are normal in any lawn and do no measurable damage.

Birds, foxes and skunks tearing holes in the lawn are a second-hand symptom: they are digging for the grubs, and their excavation often shows up before the brown does.

Drought and dry spots

Brown that follows the shape of the ground rather than a neat outline — high points, the strip along a hot path, the patch over buried rubble.

Some soils also go hydrophobic after a long dry spell: water beads and runs off instead of soaking in, so the patch stays dry through rain. Spiking the area with a fork before watering, or a wetting agent, gets water past the surface.

Disease on wet ground

Moist soil plus defined circular or ring-shaped patches points to a fungal problem. The durable responses are cultural rather than chemical:

Water deeply and early in the day, so the lawn is dry before nightfall
Aerate if the screwdriver struggles — compaction keeps soil wet and roots shallow
Feed a hungry lawn. Several common turf diseases are worst in low-nitrogen grass

Dog urine

The dark green ring is the tell

It is a nitrogen overdose, not a burn. The centre gets too much and dies; the diluted edge gets a useful dose and grows darker and faster. No disease does that. Soaking the spot with water within a few hours prevents most of the damage.

Reseeding, and when it is needed

Grasses that spread by rhizomes or stolons will close small patches themselves over a season. Bunch-forming types — tall fescue, perennial ryegrass — do not travel sideways, so a dead patch stays bare until you seed it.

Either way: fix the cause first. Seed sown into grub-infested or compacted ground is a second round of the same problem.

Common questions

Why does my lawn have brown patches?

Pull at the edge of one patch — that single test splits the causes. If the turf lifts away like a loose rug with no roots holding it, grubs have eaten the roots from below. If it holds firm and the soil beneath is bone dry and hard, it is drought or a hydrophobic dry spot. If it holds firm over wet soil, you are looking at a fungal disease or compaction. Small sharply defined patches with a ring of darker, taller grass around them are dog urine. And strips that match your mowing pattern are the mower, not the lawn.

How do I know if grubs are causing my brown patches?

Lift a corner of the patch. Grub-damaged turf peels back easily because the roots have been chewed off, and you will usually find pale C-shaped larvae in the top few centimetres of soil. A rough threshold is more than about five to ten grubs per square foot before the damage is theirs rather than incidental. A second clue is birds, skunks or foxes tearing at the lawn — they are digging for the grubs, and their damage often arrives before you notice the brown.

Why does dog urine make round brown spots?

It is a nitrogen overdose, not a chemical burn. Urine delivers far more nitrogen in one spot than the grass can use, so the centre scorches while the diluted edge gets a useful dose — which is why the dead circle usually sits inside a ring of darker, faster-growing grass. That ring is the giveaway, and no disease produces it. Watering the spot heavily within a few hours dilutes the dose enough to prevent most of the damage.

Will brown patches in a lawn grow back?

It depends on the grass type and the cause. Spreading grasses that run by rhizomes or stolons will close small patches themselves over a season. Bunch-forming types such as tall fescue and perennial ryegrass do not spread sideways, so a dead patch stays bare until you overseed it. Either way, fix the cause first — reseeding into grub-infested or compacted ground just feeds the next round of damage.

Can overwatering cause brown patches?

Yes, in two ways. Constantly wet soil starves roots of oxygen, so the grass thins and browns even though it is well watered. And persistent leaf wetness, especially overnight, is what most turf fungal diseases need to get established. Watering deeply but infrequently, early in the morning, addresses both at once — the lawn dries before dark and the roots are encouraged to go deeper.

What is the difference between drought patches and disease patches?

Drought patches follow the ground — high points, shallow soil over buried rubble, the strip beside a path that soaks up heat. They have soft, irregular edges and the soil underneath is hard and dry. Disease patches tend to have more defined shapes, often circular or ring-like, and appear on soil that is moist. Pressing a screwdriver into the soil at the patch tells you which one you are dealing with faster than looking at the grass does.

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Two cream-white C-shaped chafer grubs on dark soil, showing brown head capsules and three pairs of legs

Garden Problems · Sep 18, 2026