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How to Use Wood Ash As a Fertilizer

Wood ash is the powdery substance leftover after burning firewood. While most people dispose of the ash in the trash can, others place it in their garden to use as a fertilizer. While wood ash should not be used in large quantities, small amounts can adjust the soil acidity and provide potassium.

Wood ash also provides calcium to plants.

Things You Will Need

  • Garden tiller
  • Broom
  • Shovel
  • Wood ash
  • Bow rake
  • Garden hose

Wood ash is the powdery substance leftover after burning firewood.  While most people dispose of the ash in the trash can, others place it in their garden to use as a fertilizer.

While wood ash should not be used in large quantities, small amounts can adjust the soil acidity and provide potassium.  According to the University of California, wood ash contains five to seven percent of potassium and approximately two percent of phosphorous.

The best time to spread wood ash as fertilizer is in the fall. 

  1. Position a garden tiller at the edge of the desired planting area and set the blade depth to between five and six inches. Turn the tiller on and push it over the chosen area to dig up the soil.
  2. Sweep the ashes out of your fireplace, or use a shovel to collect them from outdoor wood-burning pits or fire pits.
  3. Spread the ashes over the tilled area at a rate of five to 10 lbs. per 100 square feet of space.
  4. Rake the planting area with a bow rake to mix the wood ash into the soil well.
  5. Allow the planting area to sit undisturbed for at least three to four weeks before planting in it.
  6. Tip

    If desired, you can fertilize plants that are already in the ground by applying the wood ash on top of the ground near the plant. Spread it in a circle approximately six to 12 inches from the base of the plants. Rinse the leaves of the plants with a garden hose after the wood ash application.

    Warning

    Do not apply wood ash as fertilizer more than once per year.

Things You Will Need

  • Garden tiller
  • Broom
  • Shovel
  • Wood ash
  • Bow rake
  • Garden hose

Tip

  • If desired, you can fertilize plants that are already in the ground by applying the wood ash on top of the ground near the plant. Spread it in a circle approximately six to 12 inches from the base of the plants. Rinse the leaves of the plants with a garden hose after the wood ash application.

Warning

  • Do not apply wood ash as fertilizer more than once per year.

About the Author

Kimberly Johnson is a freelance writer whose articles have appeared in various online publications including eHow, Suite101 and Examiner. She has a degree in journalism from the University of Georgia and began writing professionally in 2001.

Photo Credits

  • Susie Cushner/Digital Vision/Getty Images
  • Susie Cushner/Digital Vision/Getty Images