Reasons Why Your Lawn Is Thinning


Mar 30, 2021

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You work hard to keep your lawn green and lush, but you may notice it’s starting to thin one day. No, that’s no lawn pattern baldness. Clearly, something’s causing your lawn to thin or become patchy.

Early diagnosis of lawn thinning is critical in treating it, as the larger the thinning patch is, the longer it takes to fix. Once you fix the cause of your thinning lawn, you can focus on restoring your lawn’s fullness by laying sod or overseeding.

Below, we run through seven common reasons why your lawn is thinning to help determine the cause and bring your yard back to normal.

Lawn Pests

Lawn pests are a leading cause of thinning grass. These yard-killing vermin can attack from the blade down or root up, making them particularly difficult to spot and control.

One of the more common pests causing thinning in secret are grubs. These white, fleshy, wormlike insects sit just beneath the soil and feast on your turf’s roots. The grass blades weaken and die without strong roots, leaving behind large thin patches with no evidence of external damage.

Identifying the pests and treating for them is the best way to combat this type of thinning.


Disease is yet another cause of thinning turf, and these diseases are often fungal. While there are many types of fungal diseases and some go away with time, the unsightly thinning that occurs can be jarring.

Fungal outbreaks generally happen in and near pooling water, so it’s critical to maintain proper lawn drainage. Poor drainage is often the effect of compacted soil, which you can fix with a little aeration. In some cases, though, the issue is your yard’s grading, leading to costlier grading services to resolve the issue.


Like you, your lawn needs the right nutrition to stay healthy. Without the right balance of nitrogen, potassium, phosphorus, and other nutrients, your lawn will likely start to thin and become patchy.

If you suspect malnutrition, pick up a soil test from your local lawn and garden store and test your soil. Most tests are do-it-yourself and require no special skills or additional testing equipment. For more in-depth tests, though, you may have to send the samples to a lab.

The test results will show you exactly what your soil lacks and how to resolve the lack of nutrients through fertilization.

Don’t grab any old fertilizer, though. Use only fertilizer with the specific nutrients your soil lacks. Too much of any one nutrient can be just as harmful as too little. The N-P-K label on the fertilizer will explain its contents. “N” is the nitrogen content, “P” os the phosphorus content, and “K” is the potassium content.

Unbalanced pH Levels

Your lawn also needs the right pH levels to survive. Most grasses thrive in slightly acidic soils in the 6-7 pH range. If the pH levels go too acidic or too alkaline, you can end up with thin spots.

Like the nutrient tests, there are pH tests too. Some require dirt samples you mix with water and test. There are also electronic diodes you can stick into your soil to test it. Either way, this test will let you know if your soil is too acidic or alkaline.

If your soil is too acidic — pH is too high — you can add elemental sulfur to your lawn to bring it down. If it’s too alkaline — pH is too low — you can add lime (the stone, not the fruit). Save the lime fruit for the celebratory drink when your lawn’s back to normal.

Improper Mowing

Mowing your grass too low reduces the amount of blade that can absorb sunlight and achieve photosynthesis. Your grass to recede without efficient photosynthesis, leaving you with unsightly thinning or bald spots.

Fix this issue by raising your mower deck to leave 2.5- to 3-inch-tall grass after each mow. This leaves plenty of grass blade for effective photosynthesis so your lawn stays full and green.

Too Much Shade

Some grass is OK with shade, but all grass needs at least some direct sunlight to survive. If you notice your grass is thinning in shady areas, it’s likely not getting the sunlight it needs.

Trim back any trees blocking the sun to allow more sunlight through. If the thinning grass persists, you may want to consider replacing it with decorative landscaping.

Improper Watering

Deep and infrequent watering is key to a healthy lawn, and improper watering is a main cause of a thinning lawn. By “deep and infrequent watering,” we mean watering two to three days per week and long enough for the water to reach 6-8 inches deep in the soil. There are also proper times and other variables that come into play when watering.

Keep in mind that it’s not always underwatering that creates an issue. Overwatering your lawn can have the same impact.

Bring Back That Lush Lawn

That thinning lawn can be disheartening. With a little investigation, though, you can determine the cause, rectify it, and work toward returning it to its lush state. Whether it’s a lack of nutrition, improper watering, pests, disease, or any other causes on our list, you can fix it.

The key to a quick recovery is to catch and address the issue early. So get out there today and find what’s making your lawn look thin.