A green lawn is the pride and joy of many homeowners. So when those lush blades of grass start to turn yellow or brown, it’s heartbreaking, to say the least.
It’s easy to forget that turf grass’s needs are not much different than those of, say, a hydrangea. Yellow grass is frequently caused by the same deficiencies, environmental stressors, and (as much as we hate to admit it!) human errors that affect our favorite garden and landscape plants.
Rest assured, it doesn’t take expert-level knowledge to diagnose and treat a yellow lawn. But the information below will definitely help you return your lawn to its previous glory!
- What Causes Grass to Turn Yellow or Brown?
- Yellow Lawn in Summer
- Yellow Lawn in Winter
- Round Yellow Patches on Lawn
- New Sod Turning Yellow
- How To Fix Yellow or Brown Grass
- Summary — Why Is My Grass Turning Yellow?
- FAQ’s Why Is My Grass Turning Yellow
Grass often turns yellow when it is stressed or damaged. The tricky part is narrowing down the source of your lawn’s discoloration from a long list of possible reasons.
Of course, yellow grass can also be a natural response to the seasons. Like the leaves of trees and shrubs, grass blades turn yellow in autumn. As long as the grass regains its green hue in the spring, this color shift is nothing to worry about!
The grass that is yellow and not showing active growth is probably dormant or dead. But telling the difference between dead and dormant grass is difficult using just the naked eye.
One trick to determine if your grass is dead or simply dormant is to pull some out of the soil. Yellow grass that freely lifts out of the dirt with zero resistance from roots is almost certainly dead. If the clump of grass won’t budge, then it’s only dormant.
Yes and no.
Much like yellow tree leaves, individual grass blades that have turned yellow won’t regain their green color. However, a section of turf that has turned yellow can put out new green growth if the root system underground remains healthy and intact.
As soon as the ground thaws and daily temperatures rise, we expect our lawns to bounce back with a flush of healthy, green growth. When that doesn’t happen (or the green quickly fades to yellow), it’s a clear sign that our lawns are not getting everything they need to thrive.
Determining the source of your yellow grass doesn’t just come down to environmental factors like drought and excess heat. You’ll also need to take into consideration things like fertilization, watering schedule, herbicide use, and how you mow your yard.
It’s common for previously healthy grass to turn yellow or brown in the middle of summer. This occurs when the season’s hot, dry weather conditions cause the grass to go dormant.
Instead of fighting to keep your lawn out of dormancy, I recommend aiming to just keep the grass alive during this period using the aptly named practice of “survival watering.” The green will return very shortly after the temperatures drop again.
Underwatering can also cause the grass to produce shallow roots. The part that throws many homeowners for a loop is that this can happen even when watering every day.
If you apply only a small amount of water to your lawn each time (no matter how frequently irrigation occurs overall), the water is only able to penetrate the very top layer of soil. Your grass will in turn keep its roots very short in order to access as much of this shallow watering as possible.
Although a shallow root system won’t automatically turn your lawn yellow, it leaves your grass super susceptible to other problems like heat stress and malnutrition. So I recommend taking steps to deepen your lawn’s roots sooner rather than later!
Compaction is caused by excess pressure on the soil’s surface. Believe it or not, the pockets of air between soil particles are as crucial to plant health as the soil itself. When soil is compacted, most of these air pockets disappear.
Vehicles are major contributors to soil compaction (there’s a reason your parents told you not to park on the grass!). Even human foot traffic can cause soil compaction. You’ll see this occur on makeshift paths and other areas people tend to walk over and over again through the grass.
Compacted soil is particularly bad news for all types of grass, largely because it stops the roots from penetrating the ground. Compacted soil also tends to lack essential nutrients, moisture, and oxygen to support healthy plant life.
Yellow and malnourished lawns tend to go hand in hand. The two most common nutritional deficiencies that cause yellow grass are iron and nitrogen.
Nutritional deficiencies can be caused by a nearly endless list of environmental factors. Simply adding more fertilizer isn’t always the answer! This is why I recommend performing a soil test before amending any assumed deficiencies in your lawn’s soil.
A case of iron chlorosis — by the way, “chlorosis” is the botanical term for insufficient chlorophyll — is not always caused by too little iron in the soil. It can also be caused by excess phosphorus or bicarbonate, which affects plants’ ability to absorb iron in the soil.
Phosphorus is one of the three main nutrients in fertilizer (it’s the middle number of any given N-P-K ratio). Be cautious not to add more phosphorus to your soil than it actually needs.
Bicarbonate is introduced to the soil indirectly via irrigation. The likelihood of having excess bicarbonate in your lawn depends on how much is in your local water supply.
Nitrogen-deficient grass can be identified by blades that turn yellow at the base first. Unlike iron chlorosis which rarely affects the veins of each grass blade, discoloration caused by nitrogen deficiency tends to affect all of the leaf tissue.
Although you can diagnose a nitrogen deficiency with the naked eye, there’s no reason to guess. Nitrogen levels are incredibly easy to test with even the simplest at-home soil testing kit.
Grass’s ability to uptake essential nutrients is largely dependent on soil pH. Specifically, soil that is too alkaline (generally, above 6.5 pH) can trigger an iron deficiency.
Yellow grass caused by elevated soil pH can look identical to a lack of iron overall. If you suspect your soil’s pH level is to blame for your discolored lawn, I definitely recommend performing a soil test.
All good things require moderation, including lawn fertilizer. If you notice your grass turn yellow shortly after applying fertilizer, then you’re probably dealing with fertilizer burn.
Prevention is the best policy when it comes to treating fertilizer burn. Measure the amount of fertilizer you are using carefully, and avoid fertilizing too frequently.
Uneven application can also burn sections of grass. I recommend investing in a quality broadcast fertilizer spreader for this reason.
Many weed killers are designed to leave your lawn unharmed. However, don’t be alarmed if the grass around the treated area still discolors slightly. The yellowing should fade away shortly.
To minimize any damage to your lawn, do not apply herbicide sprays in windy conditions. I also suggest applying weed killers in cooler weather (below 85°F).
I’m a strong believer that herbicides are powerful tools when used responsibly! Opting for a selective herbicide formula that targets specific weeds will limit the impact on your lawn and garden.
Cutting too close to the ground leaves the soil exposed to the air — moisture will quickly wick out of the soil and away from your lawn’s roots. Mowing grass too short is particularly bad when the weather is hot and dry.
If the grass immediately appears yellow after mowing, then you may have cut all the way down to the stems (an often-accidental practice known as scalping).
If your freshly mowed lawn features grass blades that are jagged and brown at the tips, it’s probably time to sharpen your mower blade.
Using a blunt blade increases the amount of damage done to the grass as you mow. This places more stress on the grass, increasing the chance it will turn yellow after cutting.
During winter, some species of grass may go into a dormant phase and turn brown, examples include Bahia, Bermuda, Centipede, St. Augustine, and Zoysia grass.
However, there are many other reasons your lawn could yellow over winter, such as suffering from disease, exposure, or becoming smothered by leftover yard debris.
Yellow grass in wintertime usually isn’t worth a second thought. The change in color is normally just a sign that your grass has stopped growing. This means any damage occurring during winter isn’t noticed until the following spring. However, let’s quickly cover some other less common reasons why your lawn may have turned yellow during winter.
Few fungal diseases remain active in the depth of winter. But if you want to protect your lawn from cold weather damage, I recommend familiarizing yourself with the signs and symptoms of fairy rings, snow mold, fusarium patch disease, and smut.
Fairy rings are fungal growths that start at a central point and gradually expand in a near-symmetrical circle.
According to the University of Wisconsin, fairy rings can be grouped into three types:
- Type 1 dries out the soil and turns the grass in the area brown
- Type 2 increases nitrogen in the soil and turns the grass dark green
- Type 3 produces mushrooms around the edge of the ring
Some people find fairy rings to be beautiful, natural phenomena. Others consider them an eyesore. Either way, a fairy ring is unlikely to cause permanent damage.
Snow mold produces circular, discolored patches of grass that often have a white crust-like coating. The fungi that cause snow mold thrive in cold weather, yet these patches aren’t visible until the snow melts.
Fungicide treatments won’t work on existing snow mold. If you’ve struggled with snow mold in the past, a preventative fungicide (as well as routine lawn care) is the best solution.
Fusarium patch disease is caused by one of the fungi responsible for snow mold. Unlike snow mold, fusarium patch disease occurs in autumn or mid-winter when there is little or no snow cover. Otherwise, the symptoms and prevention protocol are the same.
Visible evidence of smut fungi can include lightened patches of lawn, seed heads that appear blackened by soot, and grass blades bearing yellow stripes.
The recommended treatment for smut fungi is containment. Your top priorities should be maintaining a strong and healthy lawn and reducing fungal spread by mowing before flowers or seed heads emerge. Keep in mind that smut fungi thrive in nitrogen-rich soil.
Fauna and flora alike rely heavily on the snow to stay safe from harsh winter conditions. In the case of turfgrass, a covering of snow helps protect the plants from freezing temperatures and dry air.
As winter approaches, you can prepare your lawn by:
- Maintaining blade height when you mow
- Applying a specialty winterizing fertilizer
- Dispersing a thin, even covering of leaves or grass clippings
- Aerating the soil
(Different turfgrass species have different weather tolerances. I recommend researching the needs of your specific type of grass to create a custom winterizing routine.)
A thin layer of mulched grass clippings, leaves, and garden debris can protect and feed your lawn through winter and into spring. What you should not do, however, is leave piles or a thick layer of debris on any part of your lawn. This is a great way to smother the grass, which will die off by the time spring arrives.
Yellow spots on your lawn can typically be traced back to excess nitrogen. This nitrogen may be the result of a household pet or uneven fertilization. I recommend ruling these sources out before looking into other potential causes.
If you’re confident that your grass isn’t being damaged by an animal or your own maintenance routine, then the most likely culprits are insects or one of the fungal diseases discussed above.
Depending on your region, insect damage may be caused by:
- Chinch bugs
- June bugs
Urine is very high in nitrogen compounds. So when a dog (or another animal) relieves itself on your lawn, it inadvertently delivers a large dose of nitrogen to the soil. This is also why some dog urine spots will actually be greener than the grass around them.
Canine supplements that promise to prevent these yellow spots work by lowering the nitrogen content in your dog’s urine. Ensuring your pup is well-hydrated can also improve the state of your lawn.
Reseeding is the preferred (and, in most cases, the only) method for repairing yellow patches of grass caused by animal urine.
Pennington recommends flushing any remaining urine out of the topsoil with clean water to ensure the new grass won’t meet the same fate. You can then remove the dead grass and reseed it with your chosen grass variety.
Unfortunately, yellow sod is frequently caused by user error. If you encounter this problem, there’s a very good chance you are underwatering, overwatering, or fertilizing the sod too soon.
Fresh sod can dry out much faster than established grass. So frequent, thorough watering is important to giving your new lawn a strong start.
Meanwhile, overwatering new sod is a serious concern. Be sure to taper off your watering as the sod takes root to prevent oversaturating the soil.
While it’s tempting to jumpstart your lawn with a dose of fertilizer, avoid fertilizing sod for at least 30 days after it has been laid.
Since fresh sod often turns yellow when it dries out, it’s only logical that the edges would be the first to go. Remember: if the edges start to discolor, the rest of the sod isn’t far behind!
Consider how often you water and whether the sod may have been exposed to fertilizer too soon to establish the root cause of the problem, and then take action.
Sod that turns yellow in patches rather than along the seams or all over may be the result of overwatering. If you can rule that out, then the spots could be caused by fungal disease or animal urine.
Before installing fresh sod, the soil should be prepped to address any compaction issues. If it is not, there’s a high chance the sod will die off shortly after installation. Remember, compacted soil is unlikely to contain air pockets and these are vital for healthy root growth.
Yellow grass cannot be cured with a miracle elixir. Instead, you’ll need to invest in a consistent maintenance routine that meets the needs of your lawn throughout the year.
Below you’ll find everything that goes into the ideal lawn care routine. You will not necessarily need to implement all of these changes to make your grass greener. However, this outline is a wonderful way to identify areas where your current routine may be lacking:
Aeration can be done by hand or with a powered machine. Small areas can be treated with a handheld aerator without issue. You’ll want to consider renting a powered aerator for particularly large sections of grass.
Excess grass clippings or fallen leaves can smother the grass and create a home for insects and disease. Remove this debris to give your lawn a clean start.
Many homeowners have great success fertilizing their lawn once per year. Annual lawn fertilization should occur in early fall.
Sadly, it’s impossible to recommend a one-size-fits-all fertilization schedule for a healthy lawn. If yearly fertilization doesn’t work for your lawn, you’ll need to consider things like grass species, local climate, soil content, and watering schedule for the best results.
I can’t stress the importance of a soil test enough! With that said, most yellow lawns benefit greatly from a high-nitrogen fertilizer. If your grass shows signs of iron chlorosis, consider using a fertilizer with a lower phosphorus content.
I prefer slow-release granules for lawns. This format is ideal for even distribution and preventing fertilizer burn.
Chelated iron is a specially treated form of iron that is easier for plants to absorb. It is less likely to leach out of the soil or oxidize into form plants can’t use.
Chelated iron may be applied alone or as part of a multi-nutrient fertilizer formula.
The ideal time of day to mow your lawn is after the morning dew has dried but before the midday sun (and temperature) has peaked. On most days, this will be between 8 AM and 10 AM.
One of the biggest steps you can take toward a healthier lawn is to water more but less frequently. The general rule of thumb is to apply approximately one inch of water one to two times per week.
Saturating the first couple of inches of soil benefits your lawn twofold. First, it encourages your lawn to produce longer roots. Second, it ensures moisture stays in the soil for a longer period of time.
You don’t want your lawn to be damp going into the evening. Watergrass in the early morning so that the afternoon sun has plenty of time to dry the blades.
While less common of a problem than underwatering, overwatering can also take a toll on your green lawn. Take recent weather into account when watering your lawn — i.e., there’s no need to saturate the soil immediately after heavy rainfall.
Ensuring your lawnmower is always equipped with a sharp blade will minimize the damage done to each blade of grass when cut. It can also make mowing easier and faster to complete.
Plus, grass cut with a clean, sharp blade looks much better than the jagged remnants left behind by a dull one!
If your yellow grass was the result of animal urine, fertilizer burn, or another environmental stressor, be sure to address the source before adding fresh seed. Otherwise, your new grass could turn yellow as soon as it grows in.
Before removing yellow grass and reseeding, I recommend double-checking that it has truly died and is not just dormant. Remember: with proper care and some patience, dormant grass will return to green on its own!
You may be tempted to try everything in your lawn care arsenal at the first sign of yellow grass. That’s the last thing you should do!
Yellow grass can be caused by many, many factors. Each one requires a different approach, and using the wrong treatment strategy could actually make the problem worse.
Your first step when treating yellow grass should always be to accurately diagnose the cause. This can usually be done alone. However, I encourage you to consult a professional if you’re not 100% confident in your diagnosis.
With a diagnosis in hand, reversing the discoloration of your lawn should be relatively easy. From there, you can focus on building strong, healthy turf that will resist future stressors with ease!