Generally, for best results, limestone should be applied two to three months prior to planting to allow time for it to neutralize the acidity. The most important factor determining the effectiveness of lime is placement. Maximum contact of lime with the soil is essential. Most liming materials are only slightly soluble in water, so incorporation in the soil is a must for lime reaction. Even when properly mixed with the soil, lime will have little effect on pH if the soil is dry.
Moisture is essential for the lime-soil reaction to occur.
In the case of lawns, it can only be surface applied and watered into the soil. They are not as effective as limestone but with repeated use, they can drastically raise the pH value of a soil, especially if the soil is sandy in texture. Ashes should not come in contact with germinating seedlings or plant roots as they may cause damage. Spread a thin layer during the winter and incorporate into the soil in the spring. Check the soil pH annually especially if you use wood ashes.