How to make a compost more acidic
Compost material brings nutrients and moisture-rich soil to plants and gardens. In its infancy, a compost pile tends to be more acidic than alkaline. However, as it matures and reaches complete composting, the pH level raises and becomes more alkaline.
When you want to use this compost on plants that prefer an acidic soil, alkaline compost can be harmful, or at least not to the soil. However, there are some tricks you can use to raise the acid level in your compost, making it more comfortable for acid-loving plants.
Moisten a pH strip in the compost. Compare the colour of the strip with the key on the side of the box. A pH level under 7.0 is acidic. If the pH is over 7.0, you can take steps to lower the pH, or rather raise the acidity.
Add fruit waste to the compost pile. Be sure the fruits has not been contaminated by oils or fats, as these cannot be added to the compost.
Collect pine needles from local evergreen trees or Christmas trees and incorporate them into the compost pile.
Limit deciduous leaf inclusion, as these tend to be more alkaline.
Avoid adding lime, or calcium carbonate, as this will raise the alkaline level of the soil.