A lush green color is a clear sign of a healthy lawn. So when a lawn turns yellow, it’s often a sign that something’s wrong. Causes can vary from the benign, a lawn that’s simply in dormancy, to the more serious, a lawn that’s suffering from pest problems or disease. The first step to determining what, if anything, you need to do to get your lawn back to its verdant color is to diagnose the problem.
To figure out the common causes, we sought guidance from lawn expert Jose Lopez, owner and founder of Chicago-based Williams Landscaping Inc.
8 Most Common Reasons Your Lawn Is Turning Yellow
1. Dog Urine Burn
If you own a dog, there is a good chance that urine is the culprit, especially if your four-legged friend has a habit of going in the same spot. While the right amount of nitrogen drives grass growth and gives it a deep green color, too much will kill it. “Concentrated nitrogen and salts from urine can damage the grass in that spot,” Lopez says.
To determine if dog urine is what’s ailing your lawn, check to see if there are patches of dark green grass around a yellow or brown spot. Highly concentrated urine will cause the grass to yellow. As it moves outward from the spot, the urine will dilute, fertilizing the grass around the spot, causing it to turn deep green and grow more quickly.
How to Fix Dog Urine Spots on Lawn
- Hose down the area to dilute and remove excess salts and nitrogen from the urine, then monitor the area to see if it greens back up. If it doesn’t, you may need to patch the area with fresh seed.
- Pick a dedicated mulched or gravel area for your dog to pee and train them to urinate only in that spot.
- If your dog misses the spot and pees in the yard, prevent damage by immediately rinsing the area with a garden hose to dilute the urine.
2. Lawn Pests and Insect Damage
Chinch bugs and grubs are some of the most common causes of yellowing grass. Grubs munch on grass roots, while chinch bugs like to eat the stems, causing damage that turns the grass leaves yellow. In the case of grubs, the turf will peel back like carpet, and the grass will eventually turn brown. Damage from chinch bugs, which suck out the fluid from the grass and replace it with a toxin, looks similar to drought stress, with the grass having a dry, straw-like texture.
How to Treat Lawn Grubs
Grubs like to nest and feed on thatch, so dethatching your yard and aerating it will help to deter them. Treat the lawn for grubs with a preventative between late spring and mid-summer.
How to Treat Chinch Bugs
As with grubs, aerating the soil and dethatching will help to deter them. You can also treat the area with a pesticide rated for chinch bugs.
Related: We Put Dozens of Lawn and Garden Tools to the Test. These 11 Came Out on Top
3. Natural Lawn Dormancy
Your yellowing lawn could be a sign that it’s simply sleeping. Cool-season grass goes dormant after the first frost in the fall and during summer heat to protect itself from drought and extreme temperatures. If most of the lawn is yellow, it’s probably dormant.
How to Handle Dormant Grass
Don’t do anything. Your lawn will come out of dormancy on its own when the weather becomes more temperate. Resist the urge to fertilize or excessively water a dormant lawn, as doing so could cause it to wake up prematurely, making it susceptible to damage from extreme temperatures.
4. Overwatering or Underwatering Mistakes
This can be tricky. Both overwatering and underwatering your lawn can cause it to turn yellow. There is a way to figure out which one is the problem, though. If your lawn feels spongy or if you’ve noticed mushrooms beginning to sprout, you’re overwatering. “Too much water, either from watering too frequently or heavy rainfall, can stress out grass roots by making it difficult for them to get the oxygen they require to thrive,” Lopez says.
Underwatered lawns, on the other hand, feel crispy and dry like straw, with leaves that usually wilt prior to turning yellow.
How to Fix Lawn Watering Issues
- Use an old tuna can in the yard as a rain gauge. Once the can fills up, your lawn has gotten one inch of water.
- Water your lawn properly by aiming for about 1 inch to 1.5 inches of water per week, including irrigation and rainfall.
- If the ground feels soggy, cut back on watering and check whether the soil drains properly.
- During dry conditions, water twice a week to make up for the rain.
5. Fungal Lawn Diseases
Fungal diseases are a common cause of a lawn turning yellow, especially during humid, wet weather or when snow melts. Most lawn diseases will only appear on parts of the lawn as opposed to the entire lawn:
Dollar Spot
This disease consists of small circular patches of yellow, straw colored grass that are about the size of a silver dollar (hence the name). It often has web-like growths on it that are visible in the morning dew. Treat dollar spot by applying a fungicide designed for this disease. Going forward, you can prevent dollar spot from forming by avoiding overwatering.
Yellow Patch
This fungal disease consists of circular patches of rings that are yellow or reddish-brown and typically appear during wet weather in the spring or fall. Since yellow patch usually disappears with drier weather, no treatment is usually required. Avoid fertilizing and space out mowings until it recovers.
Snow Mold
Melting snow in the early spring creates damp conditions that are right for snow mold, which presents as circular patches or matted yellow areas with a telltale white or pink web. Grass usually recovers from snow mold as temperatures warm and the lawn dries out.
Related: When Should You Stop Watering Your Lawn for the Season? Look for These Signs
6. Improper Fertilizer Application
While fertilizer can spur grass growth and cause it to turn a deeper green color, applying too much can have the opposite effect. Using too much fertilizer releases high levels of salts in the soil, which can burn the grass, dehydrating it and causing it to turn yellow or a crispy brown. Failing to water the grass immediately after adding fertilizer or applying it during intense heat or drought also increases the likelihood of fertilizer turning grass yellow.
How to Fix Fertilizer Burn on Lawns
Avoid adding more fertilizer, then flush the area by watering it deeply every morning for about a week to flush the salts and nitrogen past the lawn’s root zone. Avoid mowing until the grass has recovered to avoid stressing it further. Monitor the grass for new growth. If weeks pass without any, you’ll need to repair the area by reseeding.
7. Dull Mower Blades
You can also turn your lawn yellow by cutting it with blunt lawnmower blades. That’s because dull blades will tear the grass instead of cutting it cleanly. “If the blade isn’t maintained properly and becomes dull, it will tear at the grass during cutting, leaving tips brown and ragged-looking,” Lopez says. These ragged edges can cause the tips of the grass to dry out and turn yellow or brown a day or two after mowing. Along with turning yellow, a ragged edge on the grass also makes it more susceptible to disease and heat stress, which can also turn it yellow.
How to Fix Lawn Mowing Damage
Start by sharpening or replacing the mower blades. Mowing the lawn too low can also cause it to turn yellow, so check the mower height and make sure you’re cutting no more than one-third of the grass blade at a time.
8. Soil Nitrogen Deficiency
Just as too much fertilizer can cause your lawn to turn yellow, so too can too little fertilizer. A shortage of nitrogen, the main fuel for grass growth, can cause your lawn to turn a pale yellow-green color. Look carefully at the grass blades. If the base of the leaves is yellow while the top of the leaves are green, it’s likely a nitrogen deficiency.
How to Fix Nitrogen-Deficient Soil
Apply a slow-release fertilizer with nitrogen, carefully following the application instructions listed on the bag.
Related: The Winter Watering Mistake That Can Wreck Your Grass
Frequently Asked Questions
Will yellow grass turn green again?
Whether yellow grass will turn green again depends on the cause. Grass that has turned yellow due to drought, nitrogen deficiency, or dull mower blades will turn green once weather conditions improve or the issue causing the grass to turn yellow (dull blade, overfertilizing) is fixed. “As long as the grass is still alive and you can address the cause,” Lopez says. “But if you have a patch of dead grass, there’s nothing that will help it other than reseeding or replacing it.”
What fertilizer is best for yellow grass?
Don’t fertilize your grass simply because it’s turned yellow, Lopez advises. “If the soil is too soggy or compacted, adding more nutrients won’t fix the underlying problem,” he says. “If the grass is already suffering from fertilizer burn, adding more fertilizer can make matters worse.” Instead, Lopez recommends conducting a soil test to determine if nutrient deficiency is the problem. “Once you know what it needs, choose a suitable lawn fertilizer and apply it according to the directions,” he says.
