Soil pH is the hidden factor that dictates the health of your lawn. Even if you water perfectly and apply premium fertilizers, an imbalanced pH can lock up nutrients, rendering them unavailable to your grass roots and stunting growth.
What is Soil pH?
Soil pH measures the acidity or alkalinity of your soil on a scale from 0 to 14. A pH of 7.0 is neutral. Most turfgrasses thrive in a slightly acidic environment, typically between 6.0 and 7.0, where essential nutrients are most soluble.
The Consequences of High or Low pH
If the soil is too acidic (low pH), macronutrients like nitrogen, phosphorus, and potassium become less available, while toxic elements like aluminum can increase. If it's too alkaline (high pH), micronutrients like iron and manganese get locked away, causing yellowing grass.
Testing Your Soil
You cannot determine soil pH by looking at it. A professional soil test provides an accurate pH reading and a detailed breakdown of nutrient levels. DIY test kits are available, but professional lab tests offer the precision needed for accurate corrections.
Raising pH with Lime
If your soil is too acidic, you will need to apply agricultural lime. Lime contains calcium carbonate, which neutralizes acidity over time. Because it works slowly, fall is the best time to apply lime, allowing it to break down over the winter.
Lowering pH with Sulfur
Alkaline soils require elemental sulfur or aluminum sulfate to lower the pH. This process is generally slower and more challenging than raising pH. Consistent applications of organic matter, like peat moss or compost, can also gradually acidify the soil.