The Ideal Soil pH Level for St. Augustine Grass

The ideal soil pH range for St. Augustine grass is between 6.0 and 7.0, with the optimal range being 6.5 to 7.0. This slightly acidic to neutral pH allows the grass to thrive and grow its best. Understanding the factors that affect soil pH, balancing techniques, and potential contaminants is crucial for maintaining a healthy St. Augustine lawn.

Factors Affecting Soil pH

Alkaline Soil

St. Augustine grass can struggle in highly alkaline soils, which can lead to issues like fungal diseases. A soil pH of 8.0 is considered very alkaline and may require amendments like sulfur or sphagnum peat moss to lower the pH.

Acidic Soil

On the other hand, acidic soils can also be detrimental to St. Augustine grass. A pH range of 4.2 to 5.1 is considered very acidic and may require the addition of limestone to raise the pH.

Balancing Soil pH

Lime Application

For acidic soils, dolomitic limestone can be used to raise the pH. It is recommended to apply lime in multiple small doses over a period of time, as it works slowly. A typical application rate is 10 pounds of lime per 1000 square feet, applied in several applications.

Sulfur Application

For alkaline soils, sulfur can be used to lower the pH. A recommended application rate is 5 pounds of pelletized sulfur per 1000 square feet.

Contaminants and Chemicals

Fungicides

Overuse of fungicides can harm St. Augustine grass. It is essential to use them judiciously and only when necessary.

Phosphorus

While phosphorus is an essential nutrient, excessive application can lead to issues. Soil tests should be conducted to determine if phosphorus is needed, and it should only be applied when necessary.

Home Remedies and Alternatives

Sphagnum Peat Moss

Sphagnum peat moss can help lower soil pH and also has benefits for TARR (Take-All Root Rot).

Organic Fertilizers

Using organic fertilizers can help maintain a balanced soil pH and reduce the need for chemical amendments.

History and Additional Information

Soil Testing

Regular soil testing is crucial to determine the pH and nutrient levels in the soil. This helps in making informed decisions about amendments and fertilizers.

Regional Variations

Soil pH requirements can vary depending on the region. For example, in south Florida, St. Augustine grass grows year-round and may require different pH management strategies.