Photo/Illustration: Melisa Lucas
Suppose a soil test or off-color leaves (browning around the edges) suggests that your soil lacks potassium, a major plant nutrient (the “K” in N-P-K). Rather than reach for a bag of 10-10-10, which is 10 percent potassium, you could, instead, add this nutrient by spreading wood ashes. Depending on the kind of wood burned, wood ashes contain 3 to 7 percent potassium plus an array of other nutrients in lesser amounts. Wood ashes, however, also decrease soil acidity. If overapplied (more than 20 pounds per thousand square feet), they can be detrimental to some plants. I never sprinkle the ashes beneath rhododendrons, blueberries, or other plants that require acidic soil.