How to Use Fireplace Ashes for Soil pH

Wood ashes contain potassium, which changes to lye, an alkaline substance, when it comes in contact with soil moisture. That chemical reaction raises the pH of your garden soil. Before you incorporate fireplace ashes into the ground, submit a soil sample to the county cooperative extension service for analysis. The lab test result will indicate how much limestone to add to the ground if it is too acidic for the crop you intend to grow. To substitute ashes for lime, multiply by 2 the recommended amount of pulverized limestone to determine how much ash you should till into the soil.

Things You'll Need

• Rototiller
• Shovel (optional)
• Rake

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Instructions

1. • 1

     Rototill the ground surface to a depth of 6 inches in winter. Amend the soil before the growing season to prevent the salts in the ashes from burning the seeds and seedlings' roots.

   • 2

     Broadcast the correct amount of fireplace ashes over the turned soil. If the soil analysis recommends 2 lbs. lime per 1,000 square feet, for example, apply 4 lbs. ashes per 1,000 square feet.

   • 3

     Incorporate the ashes into the ground uniformly with a shovel or rototiller. Rake the surface to smooth it out. Plant your garden in spring as you normally would.