How to Add Wood Ash to Soil


Wood ash contains potassium as well as phosphate in small amounts, as well as trace amounts of micronutrients like iron, boron, manganese and zinc. The primary component of wood ash is calcium carbonate. This acts to make the soil more alkali, much as adding lime would do. Have your garden soil tested at your local cooperative extension office to determine its pH level, then add wood ash to garden soil that is acidic or neutral to adjust the pH and enhance the soil's nutritive content.

Step 1

Test your garden soil pH using a test kit from your local cooperative extension service office. If your soil pH is higher--more alkali--than 6.5, do not apply wood ashes to the soil.

Step 2

In late winter, wearing eye protection and a dust mask, slowly shovel wood ashes from their metal can or bin into a metal wheelbarrow using a manure shovel. Inspect the ashes as you shovel them to ensure there are no smouldering embers remaining in the ashes. Fill wheelbarrow with approximately 15 pounds of wood ash ir your soil pH measures between 6.0 and 6.5; fill wheelbarrow with proportionately more wood ash if your pH measures less than (more acidic than) a pH of 6.0

Step 3

Transport the wheelbarrow to your garden area. Shovel the contents of the wheelbarrow onto garden soil and rake it out to an area about 10 feet by 10 feet square using a metal rake.

Step 4

Turn the wood ashes in to the top 6 inches of soil using a spading fork. Be certain not to leave any patches of wood ashes remaining on the soil surface.

Step 5

Repeat application of wood ashes to garden soil once a year for two more years. Retest soil pH the third year to determine whether it has shifted; if soil has become more alkaline than pH 6.5, discontinue wood ash applications for 2 years, then test soil again.

Tips and Warnings

  • Do not touch wet wood ashes. Water and ashes combine to make lye, which can cause potentially dangerous skin burns. Ensure that the wood ashes are out cold before handling them or applying them to garden soil.

Things You'll Need

  • Soil pH test kit from local cooperative extension office
  • Wood ashes
  • Spading fork
  • Manure shovel
  • Eye protection
  • Dust mask
  • Metal ash can or bin
  • Metal wheelbarrow
  • Metal rake


  • Purdue University Consumer Horticulture: Wood Ash in the Garden
  • Michigan State University Extension: Using Wood Ash

Who Can Help

  • Clemson University Extension: Soil Acidity and Liming
Keywords: wood ash, ash compost, ash soil

About this Author

Cindy Hill has practiced law since 1987 and maintained a career in freelance writing since 1978. Hill has won numerous fiction and poetry awards and has published widely in the field of law and politics. She is an adjunct instructor of ethics and communications.