Several environmental conditions can turn grass yellow.
Yellow grass is often the result of repairable conditions.
Nutrient deficiencies in the soil are fixable by reversing the situation.
Fungus and pests are common sources of yellow grass
Proper lawn maintenance can reduce occurrences of yellowing grass.
Wondering why your grass is turning yellow? Yellow spots on your lawn may indicate that action is necessary to return your grass to a healthy condition. Then again, yellowing lawn spots may be perfectly normal.
Either way, diagnosing the problem that's killing your lawn, or determining that there's no trouble at all, can tell you how to remedy the situation and get you back to enjoying your lawn worry-free.
1. Too Much or Too Little Water
Watering the grass is the most fundamental task in keeping your lawn healthy. Although your lawn can suffer from having too little water, too much can be even worse. Patches or large areas of grass that turn pale and start to yellow while displaying a thinning appearance are signs that it needs more water. On the other hand, a lawn that receives too much water will turn yellow because of other causes that result from overwatering.
How to Fix Water Quantity Problems
Repairing your too-dry lawn is a simple fix. Watering your lawn more frequently will quickly reverse the condition. Although the yellow grass blades won't become green again, new, more lively-looking grass will replace them quickly.
Lawns with damage from overwatering likely have other issues that need resolution, too. Overwatering dilutes the nutrients in the soil and leaves the grass weak and prone to fungus, lawn pests, and weeds. Allow the lawn to dry out and address the remaining issues to return your yard to a green state. A simple fix is to install a sprinkler system that you can program to water your lawn at regular intervals.
2. Too Much or Too Little Fertilizer
Your lawn needs the right mix of nutrients to keep it healthy. If you add too much lawn fertilizer, your grass can develop yellow or brown tips, wilt easily without water present, and start to look thinner. Too many nutrients, specifically nitrogen, and your lawn can become 'burned.' The affected areas will turn yellow and brown and perish in severe cases.
How to Remedy Fertilizer Trouble
If your grass is undernourished, apply a nitrogen-rich fertilizer designed to revive your lawn at your earliest convenience and establish a feeding schedule for your yard.
Repairing an over-fertilized lawn can be more challenging. If you have only minor damage, slightly overwatering your yard for a few days to dilute excess nitrogen will likely help the grass heal itself. Severe cases may require you to rake and remove the dead and dying grass and reseed your yard. To reduce the chances of over or under-feeding your lawn, carefully follow the directions and recommendations for the fertilizer you choose.
3. Pet Urine Issues
Small patches of yellow and dying grass surrounded by seemingly healthy, bright-green blades are typically memories, etched in the grass, of your dog relieving themself in that location. Dog urine kills grass because it contains nitrogen and can over-fertilize spots in your yard.
How to Neutralize Pet Urine
Unfortunately, the only way to repair the dead spots is to reseed your lawn, specifically the affected areas. To keep new spots from forming while still allowing your dog to wander free in the yard, follow closely behind with a garden hose and immediately saturate the area they choose to use as a restroom to dilute the new nitrogen.
For more convenient prevention of dog spots, you can encourage your pet to relieve themselves in a designated area, adjust the amount of fertilizer you apply to that part of the lawn, or slightly overwater your yard if it can support the extra moisture without causing other damage.
4. Poor Soil Conditions
Poor soil conditions is a general term that means the soil isn't, or is no longer, ideal for growing grass. Lawn areas with heavy foot traffic or too much water can compact over time and limit strong grass root growth, causing lawn yellowing and thinning. Inadequate nutrient supply in the soil causes damage that appears similar.
How to Repair Poor Soil Conditions
How you repair your poor soil conditions depends on what kind of soil problem exists. Compacted soil is repairable by aerating your lawn, reseeding, and developing a regular aeration schedule if the area is still subject to heavy use.
Determining what nutrients are lacking in your soil can be tricky. Test your soil to determine what nutrients you need to add and how to adjust the pH level to keep your lawn in top shape.
5. Lawn Diseases
Lawn fungus and disease are more common than you might think. They come in various forms, with names like fairy circles, yellow spot, rust, blight, and dollar spot. Some of them are treatable and preventable, while others aren't. Luckily, rust and fairy rings are easily identifiable by their telltale signatures of rusty blades or circles of oddly-colored grass. Often, diseases start in a single, small location and spread.
How to Prevent and Cure Lawn Diseases
If you can identify the type of fungus damaging your yard, you may be able to find a fungicide that can remedy the situation in the short term. A more long-term solution is to prevent fungus growth by following a lawn care maintenance checklist each season that includes aeration and consistent watering.
6. Insect Infestation
Grubs, cutworms, leatherjackets, webworms, and more make up the army of pests that can damage your lawn in chunks or as a whole. Yellowing and sometimes dead spots are the result of this common lawn problem. These pests are typically insect larvae that feed on the roots of your grass. Sometimes you can see the critters within or under the lawn thatch.
How to Treat Insect Infestations
Identification is key to treating an infestation. Once you determine what kind of insect larvae your lawn is harboring, finding the applicable pesticide at your lawn care or home center is simple. However, better ways to handle the situation include hiring a nearby professional lawn care company to address and prevent larvae from returning or following a proper lawn care schedule.
7. Dull Lawn Mower Blades
It's true—how we maintain our lawnmowers can affect the health of our yards. Dull blades or blades with extensive damage on a lawnmower breaks and crushes the grass tips instead of neatly trimming each one. You can identify the trouble by noticing dead and dried-out cut ends of grass that may split open, leaving them ripe for other problems and diseases.
As long as we're talking lawn tool maintenance—dripping oil from a leaking mower can also create dead spots in your yard.
How to Repair Mower Blade Damage
Sharpening your lawn mower blades, either as a DIY project or by taking your mower to a local lawn mower repair pro, will immediately stop the damage from worsening. To speed the healing, consider adding nitrogen-rich fertilizer if it's been a while since the last feeding.
To avoid future damage, sharpen your lawn mower blades every 25 to 30 mowing hours, raise the cutting deck to about three inches to leave enough grass behind to promote healing, and avoid mowing during excessively hot or dry weather.
8. Cold Weather
Even in moderate climates, but especially in cold locations, your lawn may go dormant and turn pale green or yellow during cold weather. It can appear to dry out and may look a little thin during this time.
How to Handle Cold Weather
A dormant lawn requires little care, and you can essentially ignore it until it begins growing again. Avoid overwatering and mowing your lawn during this time. Avoid walking on grass with frost on its surface to keep from breaking the fragile blades.
Mariel Loveland contributed to this piece.
Frequently Asked Questions
A lawn that suddenly and quickly turns yellow is typically the result of a dramatic change in the grass's environment. Heavy rainfall can dilute soil nutrients, rapidly yellowing the grass, and dull lawn mower blades can dry out and damage the grass in a short time. Over-fertilizing can yellow a lawn within a matter of days.
The best fertilizer for your lawn contains a balance of the nutrients your grass needs for long-term health. A soil test can tell you the optimum nutrient balance. However, to repair yellow grass quickly, assuming all it needs is fertilizer, apply a nitrogen-rich blend that promotes fast growth.
A soil test can tell you if your yard is experiencing acidic soil conditions, making your lawn limp, weak, and yellow. Raising the pH level by adding lime can improve the yellowing grass situation. However, lime application is only effective if acidic soil is the problem causing the yellowing.