How to Change Soil Acidity

Test the soil with a pH test kit before making adjustments to the acidity. The test results will give you a better idea of exactly how much adjustment is needed. A pH above 7.0 is considered alkaline, while a pH below 7.0 is acidic. The farther from 7.0 the pH measurement is, the more alkaline or acidic the soil is.

Add sphagnum peat or granular sulfur to the soil if you wish to reduce pH. Start by adding small amounts of peat or sulfur, mixing it into the soil and adding water to aid in the reaction between the alkaline soil and the acidic material.

Add ground limestone to acidic soil and you wish to increase the pH. Add the limestone in the same manner as the sphagnum peat or sulfur, mixing well and adding water to aid the reaction between the soil and the limestone.

Retest your soil pH over the course of several days after adding material to adjust the pH. This allows you to track the changes in your soil's acidity and determine when the changes have stabilized.

Add more pH-adjusting materials to the soil as needed, testing the soil to determine the extent of the changes. Continue adjusting the soil acidity until you reach the ideal soil pH for the plants you wish to grow.