Can I dispose of my wood ashes in the garden?
Wood ashes contain small amounts of several plant nutrients. The nutrient content of wood ashes depends on the type of wood burned, the thoroughness of its burning, and other factors. Generally, wood ashes contain 5 to 7 percent potash, 1 percent phosphate, and small amounts of other elements. However, the largest component of wood ashes is calcium carbonate. Calcium carbonate is a liming material. Liming materials raise the soil pH.
The soil pH is important because it affects the availability of essential nutrients. The pH scale runs from 0 to 14. Any pH below 7.0 is acidic and any pH above 7.0 is alkaline. A pH of 7.0 is neutral. Most vegetables, fruits, annuals, and perennials grow best in slightly acidic soils with a pH between 6.0 and 7.0. Plants may not perform as well in soils with a pH of 7.5 or above because of the reduced availability of some essential nutrients.
Avoid applying wood ashes to garden areas with a pH above 7.0. Applying wood ashes to alkaline soils may raise the soil pH to excessively high levels and reduce the availability of some plant nutrients. If the soil pH in your garden is unknown, conduct a soil test to determine the pH of your soil.