Sour (extremely acid) soils are often found in urban gardens and can be corrected with….

Powdered lime. Pulverized lime is easiest to apply. Hydrated lime is quicker acting, but may be caustic to plants if you do not apply it carefully. Use ½ pound per square yard depending on seriousness of problem. Several months after adding amendment to soil, do another soil test to verify you have added the correct amount of material.