Using Fireplace Wood Ashes in the Garden

     by Kelly McGowan, MU Extension Field Specialist in Horticulturist in the Southwest Region

      Nothing is cozier than a wood burning fireplace on a cold winter night. Once that fire is gone, ashes make a great soil amendment and have been used by gardeners for generations. Ashes are a good source of plant nutrients, especially calcium. While the calcium is good for plant health, it can work similarly to lime and effect soil pH, the acidity, neutrality, or alkalinity, of the soil. Excessive use of wood ash can lead to a pH above the ideal level, which in turn can affect nutrient availability.
     It can also increase levels of phosphorus and potassium to high levels. Be careful to not over apply and soil test every one to two years to monitor soil fertility and pH. It is easy to get too much of a good thing! The recommended amount is five to ten pounds per 100 square feet.
     Ash can be applied pre-planting and incorporated in the soil, or used as a side dressing around growing plants. Store unused ashes in a dry place. If stored outdoors, the weathering process can decrease its nutritive value.
     Make sure to only use wood ash and never ashes from burning trash. Trash burning ashes contain toxins that are undesirable in the vegetable garden. Also, keep in mind that wood ash is highly alkaline, so wear a dust mask and other protective equipment when handling to prevent inhaling or getting into your eyes.