Wood ashes as a fertilizer source?

It’s cold and the fireplace has likely been in heavy use the past week. The ash left can be an issue on multiple fronts, but if your disposal site is a garden, be careful.

Wood ashes have value as a fertilizer product. They don’t contain nitrogen, but may have a low level of phosphorous. What they contain a lot of is potassium. Unfortunately, it’s not a nutrient we tend to need much in the garden, with additions raising soil levels for no reason.

An even greater concern might be the pH effect of wood ashes. Most garden soils are not only high in P/K, but pH, too. Adding wood ashes could unnecessarily raise soil pH levels, potentially causing issues for other nutrients as well.

It might be best to discard wood ashes away from the garden altogether. If you can’t, consider a soil test to determine nutrient needs prior to application. Soil probes are available via any District Office. For less than twenty dollars, you can learn a lot about what your soil needs – and what it doesn’t.

David Hallauer59 Posts

David Hallauer is the Meadowlark Extension District agent in the areas of horticulture and crops and soils.


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