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I use a wood burning fireplace; can I put the ashes in my garden?

When wood or leaves are burned, some plant nutrients such as nitrogen and sulfur are emitted into the air along with carbon dioxide, water vapor and smoke. The alkali and alkaline earth metals, potassium, calcium, magnesium, and sodium remain in the ash as carbonates, oxides, and hydroxides. These compounds are all-alkaline and may react very rapidly to raise the soil pH. Agricultural lime, which is mostly calcium and magnesium carbonates, reacts slowly in the soil and can never raise the soil pH above 8.3 but high rates of potassium carbonate, potassium hydroxide, calcium oxide and other by-products of burning wood could raise the soil pH above 9.0. This high soil pH could create serious problems for most crops.

How to Use Wood Ashes Around the Home

As a liming material. Use only on acid soils (pH below 6.0) which need lime. Have the soil tested and spread dry wood ashes at the same rate as recommended for agricultural lime.

• 1 ton ag. lime per acre = 50 lb. per 1,000 sq. ft. =
• 50 lbs. wood ashes per 1,000 sq. ft. =
• 5 lbs. ashes per 100 sq. ft.
• 1 gallon dry ashes = approximately 3 pounds

  Although wood ashes are usually lower in percent lime (calcium carbonate equivalent), the alkaline compounds present are more reactive than agricultural lime. Therefore, pound for pound, the two are about equal in raising soil pH.

  As a source of potassium. If the soil is acid (pH below 6.0), wood ashes can be used as a source of potassium. Assuming 6 percent K2O in ashes, one ton per acre (50-lb/1,000-sq. ft.) will provide 120 pounds per acre of K2O (2.8 lb/1,000 sq. ft.). This is adequate for most gardens, lawns, and shrubs. However, nitrogen and phosphate fertilizers may still be needed. Continued use of ashes on the same site or high rates could raise the soil pH too high -- particularly in sandy soils.