What it usually means, the likely causes in order, what to safely try first, what a pro charges in Canada, and when to stop and call one.
This guide covers the common cases. Describe your exact problem and get a personalized diagnosis — free to start, with a DIY vs. call-a-pro verdict and a real cost estimate.
Brown or dead patches, thinning grass, and visible lawn pests look alarming, but they are a symptom with several very different authors: a fungal disease, a grub infestation eating roots, or a watering and mowing pattern that stresses the grass until it thins. Treating the wrong author wastes a season, so diagnosis comes before any product. Two free observations do most of the early work. Tug on the dead patch — grass that lifts like carpet with no roots points to grubs. Then look at the pattern: circular and spreading often suggests fungal trouble, while scattered damage often tracks watering gaps or pet spots.
This one worsens if delayed in a particular way: grubs keep feeding, fungal patches keep spreading in the weather that suits them, and thin areas invite weeds to colonise the bare soil. It is not a same-day emergency, but it should be assessed within the current growing season, ideally while the damage pattern is still readable. Once the lawn goes dormant or the patch is fully dead and weathered, even a professional has less evidence to work with.
Grub larvae live in the soil and chew roots, so the grass above starves and dies in irregular patches that feel spongy and lift easily because nothing anchors them. Secondary damage from birds or animals digging for the grubs often makes the patch look even worse and is itself a strong diagnostic clue.
Lawn fungi thrive in specific combinations of warmth, humidity, leaf wetness, and stressed grass. Patches that are roughly circular, expanding at the edges, with discoloured blades at the margin fit this pattern, especially after stretches of warm nights or heavy watering late in the day.
Patches that mirror a sprinkler gap, a sunny slope, or a shallow-soil area are often thirst, not disease. Scalping from mowing too low, dull blades tearing rather than cutting, and fertiliser spilled or applied unevenly can each produce dead-looking areas with healthy roots waiting underneath.
Dog urine creates small, intense patches, often with a dark green ring of over-fertilised growth around a burned centre. Salt near paths, reflected heat, and buried rubble creating shallow soil also produce scattered, repeating spots that no disease treatment will change, because the cause is an environment, not an organism.
| Job size | Typical estimate (CAD) |
|---|---|
| Simple fix — the straightforward version of this repair | $90–$150 |
| Major job — complex, hidden, or replacement-level work | $150–$500 |
Estimates only, calibrated to Greater Toronto Area trade rates and adjusted by region on this site — not a quote. Your exact price depends on the cause, parts, and access. A personalized diagnosis narrows this range using your specific symptom.
A homeowner can reasonably fix the cultural causes: adjust watering to deeper, less frequent cycles in the morning, raise the mowing height, sharpen the blade, and overseed thin areas in suitable weather. Call a lawn professional when grubs are confirmed or strongly suspected, when a fungal pattern is spreading despite corrected watering, or when patches keep returning in the same places each season. Identification is the valuable part of that visit; anyone who prescribes treatment without examining roots, blades, and soil is guessing with your money.
Start with the tug test: grub damage lifts like loose carpet because the roots are eaten away, while diseased grass usually stays rooted even as blades discolour and die. Then check the pattern and dig one small square at the patch edge to look for grubs directly. Finding grubs in numbers, plus animals digging at the lawn, settles it; finding none pushes the investigation back toward disease or stress.
It depends on whether the roots and crowns survived. Stressed or thirsty grass often recovers when watering and mowing are corrected. Grass whose roots were eaten, or crowns killed by disease, will not regrow, and those areas need reseeding or sod once the cause is controlled. The tug test and a close look at whether any green shoots remain in the patch are honest early indicators.
Repeating locations point to a fixed condition: shallow soil over rubble, a compacted path, a sprinkler shadow that never quite covers, reflected heat, or soil that stays wet and suits the same fungus. Mapping the repeats is valuable, because fixing the condition — coverage, soil depth, compaction, drainage — ends a cycle that annual treatments for the symptom alone never will.
Not blindly. Under-watered stress patches do need correct watering, but fungal problems are often worsened by wet foliage, especially from evening watering. The general pattern lawn professionals favour is watering deeply and infrequently, early in the day, so blades dry while roots get moisture. Confirm which problem you have first; the same hose helps one cause and feeds the other.
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