How to Garden in Limestone Soils


All soil has a rating on the pH scale from 1 to 10. If soil is balanced, its pH rating is 7.0. Soils with a lower rating are said to be acid, while soils with a higher rating are more alkaline. Each plant has a pH rating as well. Plants that are planted in soil that is optimal for their pH range can take up nutrients from the soil more effectively. Limestone soils are more alkaline in nature, and tend to be rated with a pH higher than 7.0. Gardeners must typically adjust the pH so that it is less alkaline in limestone soils.

Step 1

Test your soil with a pH testing kit. pH testing kits are available in many garden centers. By combining a soil sample with the included testing fluid, your soil's pH will cause the fluid to change colors. Match the soil color with the kit's color key to determine your soil's pH.

Step 2

Loosen your alkaline soil with a rototiller.

Step 3

Spread powdered sulfur or ammonium sulfate over your soil to lower the soil's pH. It typically takes 1 pound of ammonium sulfate per 10 square feet, or ¼ pound of powdered sulfur per 10 square feet to lower the pH of soil by 1.

Step 4

Mix amendments into the soil with the rototiller.

Tips and Warnings

  • Never attempt to lower your soil's pH more than 1 pH rating per year. Doing so can harm your soil's natural balance and kill beneficial microbes in the soil.

Things You'll Need

  • Soil testing kit
  • Rototiller
  • Ammonium sulfate
  • Sulfur


  • Iowa State Univeristy Extension: Garden soil management
  • Clemson State University Extension: Changing the pH of Your Soil
  • Mississippi State University: Soil pH and Fertilizers

Who Can Help

  • Iowa State University Extension: Ask the ISU Extension Garden Experts
Keywords: Adjusting soil pH, sulfur soil amendments, changing alkaline pH

About this Author

Tracy S. Morris has been a freelance writer since 2000. She has published two novels and numerous online articles. Her work has appeared in national magazines and newspapers, including "Ferrets," "CatFancy," "Lexington Herald Leader" and "The Tulsa World."