I'm Tim Fitzwater, and I get more calls about brown lawns in July and August than any other month. The first thing I tell every caller is: it's probably not drought. In my seven years working in Brandon, the four most common causes of summer brown patches are chinch bug damage, brown patch fungus, drought stress, and scalping from mowing too short. Each one has a different fix, and misdiagnosing the problem usually makes it worse — pouring more water on chinch bug damage, for example, just wastes water while the grass dies anyway. Here's how I figure out what's going on and what to do about it.

Cause 1: Chinch Bugs (Most Common)

Look for: Irregular brown patches expanding outward from sunny spots near driveways and sidewalks. The grass doesn't recover even with deep watering.

This is the cause about 60% of the time in my experience. Chinch bugs feed on St. Augustine by piercing the stems and injecting a toxin that blocks water uptake. So the grass looks droughted — dry, brown, crispy — but pouring water on it does nothing because the plant physically can't absorb water anymore. The patches start small (the size of a dinner plate), then expand as the colony moves outward.

Solution: Professional insecticide treatment immediately. Dead areas may need re-sodding because once the crowns are killed, no fertilizer brings them back. Full prevention strategy in my chinch bug prevention guide.

Cause 2: Brown Patch Fungus

Look for: Circular brown patches with a dark "smoke ring" border. Most common September–November but can show up in humid summer conditions too.

Brown patch is a fungal disease that thrives when nighttime temps stay 65–75°F with high humidity — basically most of fall and any humid stretch in summer. The classic tell is the dark ring around the perimeter of the patch, where the fungus is actively expanding. Inside the ring, grass is matted and brown.

The two things that make brown patch worse: over-fertilizing with nitrogen in heat (lush growth = more fungal food) and evening watering (wet blades overnight = fungal paradise). Both happen constantly with DIY lawn programs.

Solution: Targeted fungicide application, stop evening watering immediately, reduce nitrogen. My Lawn Health Program avoids both triggers by design.

Cause 3: Drought Stress

Look for: The entire lawn wilts uniformly — not patches. Footprints stay visible when you walk across it. Grass takes on a blue-gray tinge before going brown.

Real drought stress is rare in Brandon because we get afternoon thunderstorms most summer days. When I do see it, it's usually because either the irrigation system has broken heads/dead zones nobody's noticed, or the homeowner's been watering shallow and frequent (which produces shallow roots that can't handle a single missed cycle).

Solution: Deep watering within Hillsborough County restrictions — see my watering restrictions guide. Check irrigation for broken heads or dead zones. Recovery takes 1–2 weeks of proper watering once the cause is fixed.

Cause 4: Scalping

Look for: Brown spots that follow your mower tracks in straight lines or arcs. Grass crowns exposed and visible.

Scalping happens when you mow too short for your grass type and remove the green leaf tissue, exposing the crown (the growing point). St. Augustine should never be cut below 3.5 inches — and most homeowners I meet have their mower set at 2 or 2.5 because that's what they did up north on Kentucky bluegrass.

Solution: Raise your mower deck to 3.5–4 inches for St. Augustine immediately. Recovery takes 2–4 weeks if the crown survived. If you scalped during a heat wave and the crown died, you're re-sodding. I've seen this exact scenario destroy a brand-new front yard a homeowner just paid me to install three months earlier.

Tim's Diagnostic Process

Every brown-lawn call I get, I run through this same four-step process before recommending any treatment. You can do it yourself in about an hour:

  1. Step 1 — Water it. Deep-water the brown area. Green-up in 48 hours = drought stress, problem solved. No recovery = move to Step 2.
  2. Step 2 — Coffee can float test. Push a bottomless can into the turf at the edge of the brown patch, fill with water, wait 5 minutes. Chinch bugs float to the top. 20+ visible bugs = treatment-level infestation.
  3. Step 3 — Look for the smoke ring. A dark border around the patch perimeter is the signature of brown patch fungus. Often visible best in early morning when dew highlights the ring.
  4. Step 4 — Check your mower height. If the brown follows mowing patterns (straight lines, arcs), it's scalping. Raise the deck and rule the rest out.

When customers call me with a brown lawn, I walk through this exact diagnostic on-site. About 90% of the time one of these four matches and we have a clear path forward. The rest get a soil test and lab analysis — things like take-all root rot or nematode damage are real but much less common than the four above.

The bigger picture: most of these problems are preventable. My Lawn Health Program and sod installation service eliminate three of the four root causes by design — proper fertilizer timing, professional pest prevention, and crews trained on correct mowing heights.

Tim's Answers to Common Questions

Why does my Florida lawn turn brown in summer?
Four causes account for almost all of it: chinch bugs (most common in Brandon), brown patch fungus, drought stress, or mowing too short. Each one needs a completely different fix, and treating the wrong one usually makes it worse.
Will my brown lawn grow back?
Depends on the cause. Drought stress recovers fully with proper watering — usually within two weeks. Scalping recovers if the crown survived. But chinch-bug-killed grass and severe brown patch infections leave dead crowns behind, and dead crowns don't regrow. Those areas need re-sodding.
How do I prevent summer browning in the first place?
Great question — here's the deal: my Lawn Health Program covers preventive pest control and correct seasonal fertilization, and I train my mowing crews on proper heights for every grass type. That combination prevents three of the four most common causes by design. The fourth (drought) is solved by a working irrigation system with a rain sensor.