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WOOD ASHES - How To Use Them In The Garden

Do you have an accumulation of wood ashes from your fireplace or wood stove? They can be used in the garden as a soil additive.

Wood ashes contain potassium, some phosphorus and magnesium. Nutritional value varies according to the species of wood, according to Dr. Gary F. Griffin, an agronomist with the University of Connecticut Extension Service (6/6/81). For example, ashes from such hardwoods as maple, elm, oak and beech contain a third more calcium plus more potash than the ashes from softwoods.


Phosphorus content usually ranges between 0.8 and 3 per cent, potassium from 2.8 to 8.6 per cent, calcium from 14 to 28 per cent, magnesium from 0.8 to 2.8 per cent and sulfur from 0.3 to 0.5 per cent.

A report by Ohio State University reports that wood ashes are 40 to 50 per cent as effective as calcium carbonate in acid-neutralizing equivalent, being about 45 per cent calcium carbonate. In other words, it takes about twice as much ash to do the job of lime.

Due to the lightweight of dry ashes and their total neutralizing power, it would take a considerable amount of ash to make the soil too alkaline for good crop production. The Ohio State a report suggests that gardener's sample and tests the garden soil about every two years to monitor soils Ph.

What all this means to you is that wood ash has some nutritional value and the ability to help neutralize acid soils. So, rather than throwing those ashes away, put them to work for you by adding them to your garden.


Wood ash especially would be beneficial in areas where you have deciduous trees and shrubs, including fruit trees, vegetables (root crops), bulbs, annuals, perennials and deciduous vines. Avoid using any wood ash around such acid loving plants as rhododendrons, camellias, azaleas, junipers and conifers.

Wood ashes can be used very successfully in the vegetable garden (except in the area where you plan to grow potatoes). Mix the ash thoroughly with your soil. Tomatoes seem to benefit especially from soil that has been mixed with a small quantity of wood ash.


How much wood ash should you use in your garden? The late Bernard G. Wesenberg, a former Washington State University Extension horticulturist, recommended using one gallon of ashes per square yard on loam to clay-loam soil, and half as much on sandier soils.

If you are top dressing the lawn or flowerbeds use only about to inch of ashes per year.


Since the nutrient content of wood ashes is rather low, there is little danger of chemically burning garden plants as long as moderate amounts of wood ashes are used. (Of course, the ashes must be allowed to cool before being used in the garden.)

It is also very important to keep wood ashes dry until they are used. Otherwise, rain will leach the soluble chemicals from the ashes.

It's estimated that about 60 pounds of wood ash will accumulate from each cord of burned hardwood.


Ashes from commercial slow burning wood log products or treated wood, have not been recommended for use in the garden due to the binding agents and chemicals being used. However, manufacturers are becoming more environmentally conscious, so you might want to call or write the manufacturer and ask them if the ashes from their product can be used in the garden. Labels usually list firm names, location and often telephone numbers. Or, check with your local Cooperative Extension Service.


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