How To Fix Yellow St Augustine Grass?

St. Augustine grass is a popular choice for lawns in warm, humid climates due to its lush green appearance and ability to withstand heavy foot traffic. However, it’s not uncommon for this type of grass to turn yellow or brown, leaving homeowners scratching their heads wondering what they did wrong.

If you’re dealing with yellow St. Augustine grass and want to restore your lawn back to its former glory, then you’re in luck because there are five simple steps that you can take to fix the problem. With a little bit of effort and patience, your lawn will be the envy of the neighborhood once again.

Reasons for Yellow St. Augustine Grass

Yellow St. Augustine grass can be a frustrating sight for any homeowner, but understanding the reasons behind it can help you fix the problem and restore your lawn’s lush green color. Here are some of the most common reasons why your St. Augustine grass may be turning yellow:

Lack of Nutrients

When it comes to maintaining a healthy lawn, nutrient deficiency is one of the most common causes of yellow St. Augustine grass. This can occur when the soil lacks essential nutrients like nitrogen, phosphorus, and potassium.

One way to determine if your lawn is suffering from nutrient deficiency is to perform a soil test. This will help you identify which nutrients are lacking in your soil and how much fertilizer you need to apply.

In addition to fertilization, there are other ways to address nutrient deficiencies in your lawn. One method is to use compost or organic matter as a natural fertilizer. These materials provide slow-release nutrients that can improve soil health and promote healthy grass growth.

Another important factor in preventing nutrient deficiency is proper mowing practices. Cutting the grass too short can stress the plants and make them more susceptible to disease and insect damage. Make sure to set your mower blade at the correct height for St. Augustine grass, which is typically around 3-4 inches.

Overall, addressing nutrient deficiencies in your lawn requires a combination of proper fertilization, mowing practices, and soil health management. By taking these steps, you can ensure that your St. Augustine grass stays healthy and vibrant throughout the growing season.

Overwatering or Underwatering

Overwatering or underwatering can both cause yellow St. Augustine grass. Overwatering can lead to root rot, which prevents the roots from absorbing nutrients properly, resulting in yellow grass blades. On the other hand, underwatering can cause the grass to turn yellow due to dehydration.

To determine whether you are over or under watering your lawn, check the soil moisture level regularly. Stick a screwdriver or a garden fork into the soil and see if it goes in easily. If it does not go in easily, then the soil is too dry and needs watering. If it goes in too easily or feels soggy, then the soil is waterlogged and needs time to dry out.

If you are overwatering your lawn, reduce watering frequency and duration immediately. Water only when necessary and avoid watering during rainy periods. Ensure that your lawn has proper drainage by aerating the soil regularly.

If you are underwatering your lawn, increase watering frequency and duration gradually until you achieve optimal moisture levels for healthy growth. Water deeply but infrequently to encourage deep root growth.

Remember that St. Augustine grass prefers well-draining soil with a pH range of 5-8.5. Testing your soil pH will help you determine if an imbalance is causing yellow grass blades.

Proper watering habits are crucial for maintaining healthy St. Augustine grass and preventing yellowing due to over or underwatering. By following these tips, you can ensure that your lawn stays green and lush throughout the year!

Soil pH Imbalance

Soil pH imbalance can be a major reason for yellow St. Augustine grass. The ideal pH range for St. Augustine grass is between 5.0 and 7.5, but it can grow in slightly acidic to slightly alkaline soil.

If the soil pH is too low (acidic), it can cause nutrient deficiencies, especially in micronutrients like iron and manganese, which are essential for plant growth and development. On the other hand, if the soil pH is too high (alkaline), it can also cause nutrient deficiencies, particularly in macronutrients like nitrogen, phosphorus, and potassium.

To determine the soil pH level of your lawn, you can use a soil test kit or send a sample to a professional laboratory for analysis. Once you know the soil pH level, you can take appropriate steps to correct any imbalance.

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If the soil is too acidic, you can add lime to raise the pH level gradually. However, it’s important not to overdo it as excessive liming can also harm your lawn. Follow the recommended application rates based on your specific situation.

If the soil is too alkaline, you may need to add sulfur or an acidifying fertilizer to lower the pH level gradually. Again, follow recommended application rates carefully.

It’s important to note that correcting soil pH imbalance requires patience as it takes time for the changes to take effect. You may need to repeat applications over several months or even years until you achieve the desired results.

In summary, a proper balance of soil pH is crucial for healthy St. Augustine grass growth and development. Identify your lawn’s current pH levels and take appropriate steps to correct any imbalances gradually and carefully following recommended application rates while being patient with results taking time to show up.

Pests and Diseases

Pests and diseases can cause yellowing in St. Augustine grass. These issues can usually be identified by the presence of insects or visible signs of disease on the grass blades.

One common pest that affects St. Augustine grass is chinch bugs. These small insects feed on the sap of the grass, causing it to turn yellow and die. Other pests that can damage St. Augustine grass include armyworms and sod webworms.

Diseases such as brown patch and gray leaf spot can also cause yellowing in St. Augustine grass. Brown patch is a fungal disease that thrives in warm, humid conditions, while gray leaf spot is caused by a bacterial pathogen.

To treat pests and diseases in St. Augustine grass, it’s important to identify the specific issue first. This can usually be done by examining the affected area closely for signs of insects or disease.

Once identified, treatment options will vary depending on the type of pest or disease present. In some cases, insecticides may be necessary to control pests like chinch bugs or armyworms. Fungicides may be needed to treat fungal diseases like brown patch.

It’s important to follow all safety guidelines when handling chemicals and pesticides in order to protect yourself and others from harm.

Regular maintenance practices like proper watering, fertilization, and aeration can help prevent pests and diseases from taking hold in your St. Augustine grass lawn. By keeping your lawn healthy and well-maintained, you’ll be able to enjoy a lush green lawn all year round!

Step 1: Identify the Cause

Identifying the cause of yellow St. Augustine grass is crucial to effectively fixing the issue. There are several reasons why your grass may be turning yellow, and each requires a different solution.

One common reason for yellowing grass is lack of nutrients. St. Augustine grass needs essential nutrients such as nitrogen, phosphorus, and potassium to maintain its green color and healthy growth. Without these nutrients, the grass can turn yellow or even brown. To determine if this is the cause of your problem, you can perform a soil test to check for nutrient deficiencies.

Another reason for yellowing grass is overwatering or underwatering. Both can lead to stress on the grass roots and cause discoloration. Overwatered grass will have soggy soil and may develop fungal diseases, while underwatered grass will have dry soil and wilted blades. To identify if this is the issue, check the soil moisture level regularly and adjust watering habits accordingly.

A third reason for yellow St. Augustine grass could be an imbalance in soil pH levels. The ideal pH range for St. Augustine grass is between 5.0-7.5, with 6.0-6.5 being optimal. If the pH level falls outside of this range, it can affect nutrient uptake by the roots and lead to yellowing or browning of the blades.

Finally, pests and diseases can also cause yellowing in St. Augustine grasses such as chinch bugs or brown patch disease that damage roots or leaves leading to discoloration.

By identifying what’s causing your St Augustine Grass to turn yellow you’ll be able to take action towards fixing it with confidence in Step 2: Aerate Soil

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Step 2: Aerate the Soil

Aerating the soil is an essential step in fixing yellow St. Augustine grass. By aerating, you create small holes in the soil that allow air, water, and nutrients to penetrate deeper into the ground. This process helps to loosen compacted soil and promote root growth.

To begin the process of aerating your lawn, you will need a lawn aerator. You can rent one from a local garden center or hardware store. Once you have your aerator, follow these steps:

  1. Mow your lawn: Before aerating, make sure to mow your lawn short. This will help the aerator penetrate deeper into the soil.
  2. Water your lawn: Water your lawn thoroughly before beginning to aerate. This will help soften the soil and make it easier for the aerator to penetrate.
  3. Aerate your lawn: Begin by running the aerator over your entire lawn once in a north-south direction, then again in an east-west direction. Make sure to overlap each pass slightly to ensure complete coverage.
  4. Remove plugs: As you aerate, small plugs of soil will be removed from your lawn’s surface. Leave them there as they contain valuable nutrients that will break down and feed your grass.
  5. Repeat annually: It’s recommended that you aerate your St. Augustine grass at least once a year to maintain healthy growth and prevent yellowing.

Aerating is an important step in fixing yellow St. Augustine grass caused by compacted soil or lack of proper nutrient absorption due to poor drainage or improper watering habits. By following these simple steps annually, you can improve the overall health of your lawn and enjoy lush green grass all season long!

Step 3: Fertilize Properly

Fertilizing your St. Augustine grass is an important step in maintaining its health and vibrancy. Proper fertilization provides essential nutrients that are necessary for the growth and development of the grass. However, it’s important to fertilize properly to avoid further damage to yellowing grass.

The first thing you need to do is determine the type of fertilizer that is best suited for your St. Augustine grass. Look for a fertilizer that contains nitrogen, phosphorus, and potassium in balanced proportions. These three nutrients are essential for healthy plant growth.

When applying fertilizer, make sure to follow the instructions provided on the package carefully. Over-fertilizing can cause more harm than good and can even kill your grass. It’s recommended to apply fertilizer during the growing season, which typically runs from late spring to early fall.

It’s also important to note that too much nitrogen can lead to excessive leaf growth but weak roots, which makes your lawn more susceptible to pests and diseases. Therefore, it’s advisable not to use high-nitrogen fertilizers on St. Augustine grass.

Another factor you should consider when fertilizing your yellowing St. Augustine grass is the timing of application. Fertilizer should be applied when temperatures are mild, and there is no risk of drought or heavy rainfall within 24 hours after application.

Lastly, remember that proper watering habits complement proper fertilization practices in maintaining a healthy lawn. Watering too much or too little can affect nutrient uptake by the roots of your St. Augustine grass.

In conclusion, fertilizing properly is crucial in fixing yellowing St. Augustine grass; therefore, ensure you use balanced fertilizers with appropriate nutrients at optimum timing and rates while following safety guidelines when handling chemicals and fertilizers as recommended by manufacturers or experts in lawn care management.

Step 4: Adjust Watering Habits

Proper watering habits are crucial to maintaining healthy St. Augustine grass. Overwatering or underwatering can cause yellowing and other issues. It’s important to adjust your watering habits to ensure your lawn is getting the right amount of water.

To determine how much water your lawn needs, you should consider factors such as temperature, rainfall, and soil type. A general rule of thumb is to water deeply but infrequently. This means giving your lawn a good soaking once or twice a week rather than frequent light watering.

If you’re not sure how much water your lawn is receiving, you can use a rain gauge or a simple tuna can placed on the lawn to measure the amount of water applied during each watering session.

Another important aspect of proper watering is timing. Watering in the early morning hours (between 4 am and 10 am) allows for better absorption and reduces the risk of fungal growth. Avoid watering in the evening as this can lead to prolonged moisture on the grass blades which increases susceptibility to disease.

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Adjusting your watering habits may take some trial and error, but it’s worth it for a healthy, vibrant lawn. By following these simple steps, you’ll be well on your way to fixing yellow St. Augustine grass:

  1. Identify the cause of yellowing.
  2. Aerate the soil.
  3. Fertilize properly.
  4. Adjust watering habits.
  5. Treat pests and diseases if necessary.

Remember that consistency is key when it comes to proper watering habits for St. Augustine grass. With time and attention, you’ll be able to maintain a beautiful green lawn year-round!

Step 5: Treat Pests and Diseases

When it comes to yellow St. Augustine grass, pests and diseases can be a major culprit. In fact, some of the most common diseases that affect this type of grass include brown patch, gray leaf spot, and take-all root rot. Meanwhile, pests like chinch bugs, armyworms, and sod webworms can also wreak havoc on your lawn.

The key to treating pests and diseases in your St. Augustine grass is to identify the problem early on. This means keeping an eye out for any signs of damage or discoloration on your lawn. For example, if you notice circular patches of brown or grayish-brown grass blades with a darker ring around the outside edge, then you may have a case of brown patch disease.

Once you’ve identified the issue at hand, it’s time to take action. One effective treatment method is to apply a fungicide or insecticide directly to the affected areas of your lawn. Be sure to follow all safety guidelines when handling these chemicals and always wear protective gear like gloves and goggles.

Another option is to use natural remedies like neem oil or garlic spray to ward off pests and diseases. These products are often less toxic than traditional chemical treatments but can still be highly effective in controlling infestations.

In addition to treating existing problems, it’s important to take preventative measures as well. This includes regularly mowing your lawn at the appropriate height (usually around 3-4 inches), watering deeply but infrequently, and avoiding over-fertilization which can weaken your grass and make it more susceptible to disease.

By following these steps and staying vigilant about pest and disease control, you can help ensure that your St. Augustine grass stays healthy and vibrant year-round.

Note: Remember to follow appropriate safety guidelines when handling chemicals and fertilizers.

When it comes to fixing yellow St. Augustine grass, fertilizers and chemicals are often necessary. However, it’s important to remember that these substances can be dangerous if not handled properly. That’s why following appropriate safety guidelines is crucial.

When handling chemicals and fertilizers, always wear protective gear such as gloves, goggles, and a mask. Be sure to read the label carefully before use and follow the instructions closely. Never mix different chemicals together as this can result in toxic fumes or even explosions.

Store all chemicals and fertilizers in a secure location out of reach of children and pets. Properly dispose of any unused or expired products according to local regulations.

By following these safety guidelines, you can ensure that your efforts to fix your yellow St. Augustine grass don’t result in any harm to yourself or others. Remember, safety should always come first when dealing with potentially hazardous substances.


In conclusion, a yellow St. Augustine grass can be a sign of various underlying problems such as lack of nutrients, improper watering habits, soil pH imbalance, and pests or diseases. To fix the issue, it is essential to identify the cause first, then follow five simple steps to restore your lawn’s health.

Aeration, proper fertilization, adjusting watering habits according to the weather conditions, and treating pests and diseases are all crucial steps in bringing back your lawn’s lush green color. It is important to remember that handling chemicals and fertilizers requires appropriate safety guidelines to avoid any accidents or harm to yourself or others.

By following these simple steps and taking care of your St. Augustine grass properly, you can have a beautiful and healthy lawn for years to come.