Try Wood Ash As A Soil Fertilizer: {Good To Know}

Consider saving the ashes from this summer’s campfires, backyard fire pits and even your home’s fireplace or wood stove, did you know they can be spread throughout the garden to act as an organic soil booster? They’ll also deter pests too! Here’s how it works:

Natural Garden Booster
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Wood ashes contain potassium, calcium, phosphorus and magnesium which encourage strong root and stem growth.

It’s main benefit as a garden pick-me-up though is that it increases the soil’s alkalinity (which you’ll want if it’s acidic). It’s considered a substitute for garden lime since they both sweeten soil, though keep in mind that the ashes will produce results faster since they’re more water soluble.

Important! Don’t use if soil is alkaline, test first if you’re unsure.

How to use: Sprinkle them on top of tilled dirt then take a rake and mix in evenly, make sure to break down any clumps since a heavy concentration will result in a potentially harmful salt spot once it gets wet.

Apply when the dirt is dry, it’s not windy and at least 3 weeks before planting to give it a chance to work its magic (and not be too strong for seedlings).

How much to use: It’s advised to use no more than 25 gallons per 1000 square feet per year (source) and that you test the soil before each application.

If you’ve already planted, you can still take advantage of it by simply side-dressing around growing plants. Use it in vegetable gardens, flower beds, around shrubs and even on your lawn! Some tips: (source)

  • Rose bushes & shrubs: Treat with 1/2 to 1 pound of wood ash (per year).
  • Lawns: Apply no more than 10 to 15 pounds of ash per 1,000 square feet of lawn (only if soil pH is less than 7.0, don’t use if potassium levels are high).

Natural pest repellent? You bet! Bugs such as garden slugs and snails aren’t fond of scraping their bellies across the ashes so they’ll move on to find more friendlier ground. To be effective you’ll need to spread a fresh batch around plants after each rain, just a lightly sprinkled layer will do (a light layer also won’t sway the pH level that much so you can use it without too much concern).

They are pretty strong at first and can burn a plant’s leaves if it comes in contact with them, rinse plants well after dressing. Don’t sprinkle too close to young plants since they’re more sensitive to direct contact.


  • You can also add them to the compost pile (about every 6″ or so), this helps reduce odors and increase the rate of decomposition (not too heavy, just a light layer will do).
  • Do not use any that came from wood that had a chemical preservative applied and only use if produced from wood fires that have not included other items (since they may contain traces of harmful materials for the dirt or plants).
  • Remember, this is a substitute for lime which means it decreases a soil’s acidity. Don’t use around acid loving plants (such as blueberries).
  • Those from hardwoods contain more nutrients than found in softwoods. Also those from young wood contain more nutrients than those from older wood.
  • If the ashes were exposed to rain before being collected, are they still good to use? Not really, the nutrients will seep out with the water (which is fine when they’ve already been applied to the garden but not before).
  • Wear eye protection, a mask and gloves when handling since it can be harmful if you breathe it in or gets in your eyes.
  • How to store: keep tightly sealed in a container so they stay dry until needed.

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