How to Adjust Soil pH When Planting Grass Plugs



Grass plugs require specific characteristics to establish in a new soil and thrive. One essential characteristic is soil pH, which determines how acidic or alkaline the soil is. While most grass performs best in soil with a pH between 6 and 7, the right soil pH still depends on the grass type you are planting.

What Influences Soil pH

Different soils have different nutrient profiles, and many factors influence their nutrient makeup and soil pH. These include the type of soil and the kind of parent materials from which it was formed. For example, sandy soils are usually more acidic than loam and clay soils, particularly those formed from limestone or dolomitic lime.

Rainfall can also affect soil pH. Water passing through the soil can leach nutrients like calcium and magnesium and replace them with acidic elements like aluminum sulfate and iron.

Some soils may have been previously nutrient-rich, but the existing vegetation may have depleted it after some time. Overall, the climate, vegetation, and fertilizer practices, among other activities, generally make the soil more acidic.

Most of the soils in Florida are slightly acidic, with a median pH of 6.1. These create the optimal conditions for grass growth.


Why Should You Test Soil pH?

Whether you’re planting Bermuda, St. Augustine, or Zoysia grass plugs, assessing your soil's nutrient profile beforehand allows you to address any deficiencies or imbalances and set the optimal conditions for a healthy and more resilient lawn.

Soil pH influences a plant's ability to absorb nutrients from the soil. In cases where the soil is too alkaline or has a high pH, essential elements like iron, manganese, and phosphorus may become less soluble. This, in turn, hampers water and nutrient uptake and diminishes microorganism activity, all of which can lead to nutrient deficiencies and stunted root growth. It can also affect the color of the grass and make it more susceptible to certain diseases. Additionally, this situation indirectly contributes to soil erosion due to reduced plant growth.

A soil test provides valuable insights into the soil's pH and nutrient levels. This information can guide you in selecting the right grass type, applying fertilizers, and making soil amendments to ensure successful grass establishment and growth. 

How to Test Soil pH Levels

Soil testing can be done in two ways: Send a sample to a soil testing lab or test the soil yourself. Soil test kits are available, usually with qualitative pH test strips, to tell you where your soil's pH falls on the color-scale range.

  1. Order a testing kit online or from your local garden center.
  2. Dig a 6-inch deep soil sample.
  3. Collect at least eight samples across your lawn in a zigzag pattern.
  4. Mix the soil samples thoroughly in a large container.
  5. In a separate cup, mix equal amounts of the soil mixture and distilled water with a plastic spoon.
  6. Let the sample sit for 30 minutes.
  7. Dip a pH strip into the solution.
  8. Use the color chart included in the soil test kit to determine your soil's pH.

Alternatively, you can use a pH probe or sensor for self-testing. While taking soil samples and testing the soil yourself provides faster results, sending a sample to a lab offers more comprehensive insights and additional information, such as nutrient deficiencies and recommendations for soil amendments.

We do not recommend testing wet soil or soil that has been recently amended. These can yield inaccurate pH readings due to excess moisture, which can affect the chemical reactions in the test.


How to Change Soil pH

Based on the soil test results, you can make more informed decisions on changing the pH. Again, whether you're raising or lowering soil pH will depend on the type of grass you want to grow.

Increasing soil pH: How to Make Soil Alkaline

Raising soil pH will increase its alkalinity, and the most common method to do so is by applying amendments that consist of some form of lime, which contains alkaline components like calcium and magnesium. Some options available at most nurseries include dolomite lime, oyster shell lime, hydrated limestone, and wood ashes.

Lowering Soil pH: How to Make Soil Acidic 

Conversely, using aluminum sulfate and sulfate is an effective way to lower the pH and increase acidity. Aluminum sulfate reacts quickly, changing soil pH as soon as it dissolves into the soil. However, caution is necessary to prevent over-application, which may lead to aluminum toxicity.

Meanwhile, sulfur requires more time to transform into sulfuric acid with the aid of soil bacteria. How long it will take to convert and impact soil pH depends on factors like sulfur fineness, soil moisture, soil temperature, and the presence of the activating bacteria.

While aluminum sulfate offers a faster pH reduction and is often preferred due to its immediate effects, it has the potential to build up in the soil, which can adversely affect plant health. As a result, it's not recommended as a long-term solution. Despite taking longer to deliver results, sulfur offers a more gradual and sustainable approach to pH reduction.

For maximum effectiveness, work both materials into the soil after application. Wash off the leaves that come into contact with these materials to prevent potential leaf burn from prolonged exposure.

These soil amendments will raise or lower the pH. Still, without actually testing the soil, it becomes challenging to determine the precise amount of amendments necessary to achieve the desired pH balance in the soil for your sod plugs.

Understanding Soil Type and How it Affects pH

Alongside a soil test, adjusting pH will also depend on the soil texture—whether it's loam, sand, or clay. Each soil type has a different buffering capacity, referring to its ability to resist pH alterations or how it responds to different soil amendments.

The general rule is that the higher the buffering capacity, the greater the quantity of amendments necessary to attain optimal pH conditions. Clay soils have a higher buffering capacity than loam, which, in turn, has a higher buffer capacity than sandy soils. It means you'll have to apply more acidic or basic solutions in clay to make the same pH change in loam or sandy soils. In other words, changing the pH in well-draining and loose soils is easier than in compact soil or soil with high clay content.


Final Thoughts

Adjusting soil pH is not an easy, one-time remedy when planting sod grass plugs but rather an ongoing process to attain and maintain the desired pH and nutrient levels in your soil.

Soil conditions can evolve, influenced by factors like climate, vegetation, and fertilizer practices. This highlights the importance of regularly monitoring and checking the soil pH to allow for timely necessary adjustments. Whether it involves raising or reducing soil pH, understanding and addressing soil acidity is critical for ensuring your soil's long-term health and fertility, creating a balanced environment for optimal plant growth.

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Jamie Tedder

Jamie surrently serve as Vice President on the board for Turfgrass Producers of Florida. He currently oversees the production of all grasses throughout all farms in Florida at Bethel Farms. He is actively working with top grass breeders, researchers, producers and end users from public and private institutions around the country to stay up to date on current industry developments. Being a University of Florida graduate, he has applied that knowledge to over 22 years of experience growing spectacular grass!

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