A great way to use them is to apply them to the garden. Before we do that, we must decide which garden area would benefit from wood ashes. Ashes from hardwood trees make great soil amendment for certain types of plants. They contain nutrients like phosphorus, potassium, and other elements that will promote bloom and strengthen roots on plants such as lilacs, rosemary, and peonies, as well as certain vegetables like broccoli, cabbage, and collards. Don’t use ashes from charcoal fires or from treated lumber, because they contain chemicals that would be harmful to plants.
The addition of wood ashes can be of great help to you when growing plants that prefer alkaline soil, especially if you have acid soil like we do in Georgia. The wood ashes will sweeten the soil, making it less acidic. You must be careful where you deposit the wood ashes, because plants like blueberries, camellias, azaleas, and rhododendrons all need acid soil, and will perish if you apply wood ashes around them.
To find out what kind of soil you have, you can take a soil sample to your local County Extension Service for evaluation. For a small fee, they will send it off for testing. For more information, just call your local county extension office.
Also, as with most fertilizers, a little wood ash goes a long way. Apply no more than 20 pounds per 1000 square feet per year. Plus, wood ashes should never be applied too close to tender roots of newly planted seedlings, so it’s best to apply them to the soil well in advance of planting time. (Fall would be great!) Wood ashes are also beneficial to lawns if applied very sparingly and watered in well.
In addition to soil benefits, wood ashes make a good natural slug repellent---just encircle the vulnerable plant with a ring of ashes and the snail/slug will not cross the line! Since ashes won’t be as plentiful next summer when snails are munching, you might want to save some for later in a galvanized bucket.