You walk out to check the yard and there it is again — a patch of brown grass two feet from a working sprinkler head. Your system ran last night. The zones all activated. But something clearly isn’t right. This is one of the most common calls Goterra receives from homeowners across Polk and Hillsborough County, and the answer is almost never obvious from the surface.
A system that “runs” isn’t necessarily a system that covers your lawn correctly. There is a meaningful difference between irrigation that activates and irrigation that delivers water where the grass actually needs it.
Why Irrigation Can Run and Still Leave Brown Spots
Irrigation systems deliver water based on their design — head placement, arc settings, pressure, and runtime. When any one of those variables is off, some areas of the lawn receive adequate water and others do not. The system activates on schedule. The zones register as running. But specific areas are being chronically under-watered.
The difficulty is that the failure is often invisible during a quick visual check. A head that looks operational from a distance may be delivering water at 60 percent of its intended radius due to a partially blocked nozzle. A zone that shows “active” on the controller may have a partially closed valve cutting flow in half.
Florida Turf Research Note
St. Augustine grass — the most common residential lawn grass in Polk and Hillsborough County — shows visible water stress within 48 to 72 hours of inadequate irrigation. By the time brown patches appear on the surface, the turf has already experienced several consecutive days of insufficient moisture at the root zone.
The Zone-by-Zone Test
Before scheduling any service, spend 20 minutes walking your yard while each zone runs manually. This one step reveals more information than any remote assessment. Most controllers have a manual run or test function — activate each zone individually and observe it at close range while it runs.
What to look for while the zone runs:
- Heads that do not pop up — clogged riser, broken body, or low pressure to that zone
- Heads that pop up but spray weakly or in a tight pattern — partial nozzle blockage or pressure issue
- Heads spraying in the wrong direction — arc has rotated, usually from foot traffic or ground shift
- One area stays dry while surrounding areas are covered — head spacing gap or blocked nozzle on the adjacent head
- A zone that does not activate at all — valve, solenoid, or wiring failure
Watch where the water lands, not just whether the head pops up. A head that appears functional from ten feet away may be spraying at a 40-degree offset from its intended arc due to ground movement or rotation.
Common Causes by Symptom
Brown strips running between heads
Strip-pattern dry areas almost always indicate a head spacing or arc coverage issue. Properly designed systems achieve head-to-head coverage — each head’s spray radius extends to meet the adjacent head. When arcs have shifted, heads are too far apart for the installed nozzles, or a head was replaced with the wrong arc setting, you get consistent dry strips between heads.
Brown ring around a specific head
A dry circle immediately surrounding a head usually means that head is covering too short a radius. Common causes: nozzle is partially clogged and spraying a tight pattern instead of the intended radius; the head has settled lower than the surrounding turf and is spraying into the ground around it; or the radius was adjusted too short during a previous service.
One consistent area that never gets coverage
If the same zone of the yard stays dry across multiple irrigation cycles, there may be a head missing entirely from the coverage design, or an existing head was removed and not replaced. This also happens when landscaping — new plantings, beds, or hardscape — was added after the irrigation system was originally designed, and no heads were repositioned to maintain coverage.
An entire zone is completely dry
A zone that receives zero water despite the controller showing it as active points directly to a valve or solenoid failure. The controller sends the signal, the solenoid fails to open the valve, and the zone receives no water. This requires electrical testing of the solenoid and valve to identify whether the component or the wiring is the failure point.
| Symptom | Most Likely Cause | Professional Needed? |
|---|---|---|
| Brown strip between heads | Arc shift or spacing gap | Sometimes — arc adjustment may be accessible |
| Brown ring around a head | Nozzle clog or wrong radius | Often DIY — clean or replace nozzle |
| Entire zone dry | Valve or solenoid failure | Yes — electrical testing required |
| Weak spray, reduced coverage | Pressure issue or blocked head | Yes — pressure testing required |
| Head pops up but does not rotate | Debris in rotor | Often DIY — flush or replace head |
| Soggy area near dry area | Pipe leak reducing downstream pressure | Yes — leak location required |
The Florida Soil Factor
Polk and Hillsborough County lawns sit on soil profiles that create irrigation challenges not found in most other states. Understanding your soil type explains why some watering programs that look correct on paper still leave brown patches.
Polk County Myakka sandy soils drain extremely fast. A standard 10-minute irrigation runtime may deliver water that passes below the root zone before the grass can absorb it. The solution is cycle-and-soak programming — multiple short runtimes with rest intervals — which allows slower penetration and absorption at root depth.
Hillsborough County spodic hardpan soils create a different problem. Sandy topsoil drains quickly, but an organic hardpan layer 18 to 30 inches below the surface blocks deeper percolation. Water perches above the hardpan, and areas with poor surface drainage accumulate moisture while adjacent elevated areas remain dry. Single long runtimes on these soils often cause runoff before the water can penetrate at all.
SWFWMD Water Use Report
The Southwest Florida Water Management District has identified improper irrigation scheduling as the leading cause of both turf drought stress and overwatering in Central Florida residential properties. Cycle-and-soak programming is specifically recommended for Myakka sandy soils throughout the SWFWMD service area.
The Water Restriction Factor
SWFWMD Phase III is currently limiting all irrigation in Polk and Hillsborough County to one day per week based on address number. This is a significant restriction, and it means your system’s programming on that single permitted day must be doing real work — not just running.
If your system was programmed during Phase I or Phase II (two days per week), the runtime per session may be too short to compensate for the reduced frequency. Brown spots that appeared or worsened after Phase III was declared in late 2025 are often a programming issue, not a mechanical one.
Separately, if your controller was never updated for your address’s correct designated watering day, your system may be running on a non-permitted day — which creates both a compliance risk and a scheduling gap that leaves your lawn without water on the correct day.
Goterra updates the controller programming at every service visit — verifying your watering day, start times, and run duration against current SWFWMD Phase III requirements. Find your permitted watering day here.
When to Call a Professional
Some causes of brown spots are accessible to a homeowner with basic comfort around irrigation systems — cleaning a nozzle, adjusting a head arc within easy reach, or identifying a head that isn’t popping up. However, most of the root causes above require proper tools and training:
- Pressure testing requires a gauge and understanding of your system’s design specifications
- Valve and solenoid testing requires electrical diagnostics
- Pipe leaks require the break to be located before excavation — random digging damages pipe and wastes time
- Cycle-and-soak programming requires knowing your soil type and adjusting runtime fractions accurately
- Controller updates for SWFWMD compliance require knowing the current Phase III schedule for your address
A Goterra free inspection covers all of it — every zone run, every head observed, pressure noted at key points, controller reviewed and updated for current restrictions, and a written report of every finding. You know exactly what’s wrong and what it costs to fix before spending anything.