pH (potential hydrogen) is a scale that ranks acidity or alkalinity of a substance. pH is measured on a scale from 0-14. A pH of 7 is considered neutral pH. pH is used to measure soil acidity to determine if soil has ideal level for the species of plant being cultivated. Ideal pH for most lawn grasses is slightly acidic around 6.4, ideal range is (5.9 – 6.9). Most grass species are very adaptive to a wide range of pH and can thrive outside of ideal pH levels. If your soil test results indicate that your soil’s pH is outside the optimal range (5.9 – 6.9) don’t fret! There are actions you can take to give your grass the ideal nutrients it requires in an imperfect pH environment. Another popular choice is using soil amendments to help get your pH into a more optimal level.
Regions* – Generally soils west of the Mississippi have higher pH levels, the Pacific NorthWest being an exception to this rule.
Action Point – Above 8.1 pH
Actions to Lower pH
Peat Moss – Peat moss will add both Organic Matter and lower pH levels. It can be lightly top dressed into your lawn ¼- ½. Make sure the grass blades are well above the level of the peat after raked in. This process can be repeated yearly for best long term results.
Sulfur – elemental sulphur is a solid choice to make soil more acidic. It takes effect slowly. Follow manufacturers directions for applications.
Compost – Similar to peat moss your adding organic matter to the soil as well as adding a mildly acidic substance. This process can be repeated yearly for best long term results.
Regions* – Midwest, Great Lakes
Action Point – no action needed
Regions* – Eastern, Southeastern, Pacific Northwest
Action Point – below 5.4 pH or so it may be a good idea to consider amending your soil.
Actions to Raise pH:
Lime: By far the most popular to raise pH is to use lime. There are two types of limestone that you will commonly see Dolomitic limestone and calcitic limestone. Both are good choices to raise soil pH. Look for a pelletized version as this will be easier to spread evenly. You want to avoid hydrated lime as you can easily over apply this type of lime. Follow manufacturers directions for applying lime, note that application rates will vary significantly for your soil type.
Wood ash – another method to raise pH, it is an excellent way to recycle your burnt ashes from your fireplace or fire pit. It generally best to use this when re-establishing a lawn area as it should be mixed into the soil. Wood ash can also be mixed into compost to increase pH of compost.
*Keep in mind the region soil types can vary significantly from the regional pH generalizations listed below.