Brown patches in August — heat, grubs, or your sprinkler?
Lawn Care 3 min read
Three very different problems that look identical from the porch. Here's how to tell them apart in about two minutes, before you waste money treating the wrong one.
August is when the phone starts ringing about brown patches. Nine times out of ten the caller has already bought something to spray on it — usually the wrong thing.
Heat stress, grub damage and a bad sprinkler head all produce brown grass. They need completely different responses, and you can tell them apart without any equipment.
#The tug test settles it in ten seconds
Grab a handful of the brown grass and pull.
- It resists — roots are intact. This is drought or heat stress, or a coverage problem.
- It lifts like a rug, with no roots attached — something ate the roots. That’s grubs.
That single test rules out the most expensive misdiagnosis. Grub treatment on a heat-stressed lawn does nothing except cost money.
#If the roots held: look at the shape
The outline tells you which of the two remaining causes it is.
| Pattern | Almost always |
|---|---|
| Wedges, arcs, or a dry stripe between two heads | Sprinkler coverage |
| Browning along driveways, walls and south-facing edges | Reflected heat |
| Whole lawn dull and blue-gray, footprints stay visible | Under-watered overall |
| Sharp-edged rectangles or circles | Something was left sitting there |
That blue-gray cast with lingering footprints is the earliest warning sign there is. A healthy lawn springs back; a thirsty one holds the print because the cells have lost turgor. If you catch it there, you’re a day ahead of visible browning.
#If it lifted like a rug: confirm before you treat
Cut a square foot of turf and fold it back. Count the white C-shaped larvae in the top couple of inches of soil.
- Under 5 per square foot — normal. Leave it alone.
- 5 to 10 — borderline. A healthy lawn shrugs this off; a stressed one won’t.
- Over 10 — that’s your problem.
Also check for secondary damage: skunks and birds tearing the turf up is them going after the grubs, not them causing the damage.
Timing matters. Grub control works on young larvae feeding near the surface. By late summer they’re bigger and much harder to kill, and by autumn they’ve moved down. Treating in August is usually the last useful window.
#Don’t fix August damage in August
The instinct is to reseed the bare patch immediately. Resist it.
Seed dropped into 90°F soil needs constant moisture to survive and mostly won’t. Wait for the first week of September, when nights cool off — that’s the best seeding window of the year here, and the repair will actually take.
In the meantime: water deeper and less often, raise the mower, and stop fertilizing until the heat breaks. Nitrogen on a heat-stressed lawn pushes growth the roots can’t support.
If you’d rather someone else worked out which of the three it is, we cover lawn maintenance and pest control across Gardnerville, Minden, Carson City and Reno. Get in touch and we’ll come and look.
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