Acidify soil in a garden by testing the soil to determine the increase in acidity required. Then, work elemental sulfur into the soil, retest the soil after a few months, and add more sulfur as needed. Avoid adding so much sulfur, as this can reduce the pH too much.
- Test the soil
Check with your county extension agent to determine your soil testing options. Results from a soil lab are more reliable than those from a self-test kit. Do not attempt to add chemicals to the soil without testing.
- Add sulfur to the soil
If the test results indicate a need to acidify the soil, add elemental sulfur at the rate of 1 to 2 pounds per 25 square feet at the end of the growing season. At this rate, sulfur lowers the pH by approximately 1 point. For highly alkaline soils, double the application rate. Avoid reducing the pH to lower than the recommended range for the plants you are growing, as this slows the growth rate of plants.
- Retest the soil
Have the soil tested again before planting season. If the pH is still too high, add more sulfur. Once you reach the desired pH range, have the soil tested every three years to determine when to add more sulfur to maintain the correct range.