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No one wants to look out on a lawn filled with yellow grass. But the good news is that the problem is quickly remedied so long as you identify the cause.
The most common reasons that grass turns yellow are too much water, too little water, disease, pests, lack of nutrients, over-fertilization, pet urine, soil compaction, and chemical spillages. Nutrients such as nitrogen, potassium, and phosphorus are essential to maintaining a healthy, green lawn.
In this article, you’ll learn:
- The 7 reasons why grass turns yellow
- How seasonal changes turn grass yellow
- Why grass may turn yellow after fertilizing
- How to restore a lush, green lawn
7 Causes of Yellow Grass
Yellow grass will ruin an otherwise perfect lawn, and there are many causes for this to happen. So, what does it mean if grass turns yellow, and can yellow grass turn green again?
Here are the most frequent reasons why grass turns yellow:
1. Too Much or Not Enough Water
Your grass is sensitive to the water levels in the soil, so the roots will not be able to oxygenate if there is too much. With too little water, the grass will go into a dormant state, lowering its defenses against disease and stress.
Though getting the soil water level wrong is one of the most common issues, it is one of the easiest to correct.
2. Diseases, Grubs, and Insects
All plant life is open to attack from a range of creatures, fungi, and other diseases. Circular yellow and bright green patches of grass are signs of fungal growth. You can check by digging up small sections and looking for dark and rotting roots.
Thin grass and dead patches also hint at a fungus or a grub infestation growing beneath the turf.
3. Lack of Nitrogen
Healthy grass depends on a steady supply of nitrogen from the soil. A lack of nitrogen will cause the blades of grass to turn yellow. Your grass may also be lacking phosphorus and potassium.
4. Over Fertilizing
As with watering, it is possible to ruin the delicate balance of your soil’s pH by over-fertilizing. An ideal pH range for your grass is between 6.0 and 6.5. If you are unsure, it is worth evaluating your soil’s pH level before changing your grass maintenance routine.
5. Pet Urine
Any animal that urinates on your grass, including dogs and cats, will ruin the soil’s pH levels. Due to the volume, dogs’ urine is more of a problem and will cause large yellow patches to appear.
6. Soil Compaction
Your grass is happiest if it can root into the soil, but compaction will prevent this. Hard soil will deprive the grass of water and nutrients, turning it yellow. Compaction can also occur in areas of foot traffic or where people are playing games, such as soccer.
7. Spilled Chemicals
Pouring old oil, wastewater, and paint over the grass or into the soil is a terrible idea. Any foreign chemicals will ruin the soil and kill everything in that immediate area, and even run off further along the grass, turning it all yellow.
Seasonal Changes Turning Grass Yellow
Any time of year when the weather makes a drastic change, your grass will stress and begin to yellow. Excessive heat, cold, and rain will all affect the appearance and health of your lawn.
Though you may think that the spring would be good for vegetation, rotting organic matter can unbalance the pH levels in the soil. As the fallen leaves thaw, they release carbon and iron.
The microorganisms that eat the carbon in the dead material decrease the nitrogen levels in the soil. Low concentrations of iron are a common phenomenon during the spring, which also cause yellow spots over the turf.
Heatwaves that last more than a couple of days will yellow your perfect grass and can even kill it. The heat can make its way down through the blades and into the soil, drying up the roots. You may be able to save the grass if you water the grass at night.
Winter desiccation happens to grass in areas with little protection from frost and wind. As frigid air blows across the blades, it freezes them and turns them yellow. Heavy freezing can cause snow molds to form as the grass thaws and rots.
Grass Turning Yellow After Fertilizing
Most people that have a lawn want to do everything they can to keep it healthy and looking green. Adding nutrients to the soil helps, but too much can cause fertilizer burn, which will yellow the grass.
Heavy use of fertilizer will weaken the grass and make it more susceptible to disease and pest infestations. You can try fixing mild cases of fertilizer burn by spraying down the yellow area with water to wash it out.
Best Fertilizer for Yellow Grass
The best fertilizers consist of nutrients nitrogen, phosphorous, and potassium. Nitrogen (N) helps with the growth rate of the blades and the intensity of green. Phosphorous (P) nurtures the roots, allowing the grass to consume more nutrients.
Potassium (K) is good for overall health. You want to see an equal mix of 10 percent of each nutrient in a bag of fertilizer. This mix may be written as N-P-K On the fertilizer bag.
A good blend is BioAdvanced’s Slow Conditioner, perfect for application over yellow grass during both warm and cold seasons.
How to Fix Yellow Grass
The methods of fixing and preventing yellow grass are the same. You can follow the easy guide below to keep your grass looking healthy and green.
What You’ll Need:
- Aerator Shoes
- Soil Meter
- Grass Fertilizer
- Grass Insecticide/Fungicide
1. Too Much or Not Enough Water
Aerate the grass with spiking sandals. This tool will improve drainage and the level of oxygen at the grass’s roots. These sandals strap on to any footwear and will help loosen the soil with 2.2-inch spikes.
After a heatwave, you will want to spray the grass with water for a few days to bring it back to green.
2. Diseases, Grubs, and Insects
If you cut and lift a small section of turf, you may see fungus, small insects, and grubs eating away at the roots. Use a hose-attachable pesticide, which will mix with the water coming through the hose, to kill off foreign invaders.
3. Lack of Nitrogen and Over Fertilizing
Test the soil with an inexpensive pH meter. This meter will also tell you if the grass is at the right moisture and sunlight level.
A high pH level tells you to stop fertilizing for a while and to add iron supplements and water to the area to bring the pH back down. A low pH means you need to increase nitrogen levels by adding fertilizer.
4. Pet Urine
If you have a dog, and the yellow grass is localized, then there is a good chance it is the urine causing it. section off the area, or the whole lawn, from the pet to allow the grass to restore itself.
5. Soil Compaction
The regular use of spiking sandals will help combat soil compaction and prevent the buildup of moisture, which causes rot and mold.
6. Spilled Chemicals
Drench the area with water to wash the chemicals below the level of the roots. Avoid parking vehicles and lawnmowers on your lawn and dispose of wastewater properly.
Gasoline will float on water, so use sand to soak up the remaining fuel from the lawn. The gasoline will eventually evaporate from the sand, and the sand will fall through to the soil.
Frequently Asked Questions
One of the most often asked questions on what turns grass yellow.
Why Is My Fescue Grass Turning Yellow?
Fescue grass tends to turn yellow when the pH of the soil or surface is unbalanced. Dog urine, drought, flooding, lack of nutrients, and over-fertilizing can all cause yellow patches. Heatwaves and fungus can also reach the roots, killing the grass from beneath.