Using Wood Ashes In the Garden!
After the long winter many New Hampshire residents are faced with a different type of problem. What does one do with the wood ashes left from their wood burning stove or fireplace? An average cord of wood, depending on the efficiency of combustion and wood type, will yield approximately twenty pounds of ashes or the equivalent of one five-gallon pail. Over the winter, this can add up to quite an accumulation of wood ashes.

Wood ash acts on the soil much like limestone in that it raises the pH or alkalinity of the soil. Consequently, many wood stove burners dump the ashes on their garden site with the thought that they are improving the soil condition of their garden. Yet unlike limestone, which can take six months sunfloweror more to take effect, wood ash has high water solubility and quickly changes the soil pH. This can cause a problem with raising the soil pH over the optimum level of 6.5 to 7.0 if we spread too many ashes in the same area. A soil pH over the optimum level can affect plants as adversely as a pH that is too low. High pH will limit the uptake of important soil nutrients needed by the plant such as phosphorous, iron, and magnesium.

A safe rate of wood ash application for a garden or lawn area would be twenty pounds per thousand square feet or a five-gallon pail full of wood ash. Twenty pounds of wood ash is equivalent to six pounds of ground limestone per thousand square feet. If the soil is in the proper pH range, this rate of application is considered appropriate for yearly treatments. After wood ash application, we should need no additional lime, with nitrogen and possibly phosphorous being the other plant nutrient requirements. The wood application will also supply potassium. We should mix the application of wood ash to the garden soil well.

The UNH soil-testing laboratory, in Durham, has recorded very high pH values from soil samples that we have treated with wood ash. Having a soil test taken once every two years from your garden and lawn is wise. The recommendations for soil treatment, including any adjustment of soil pH, will give one a more accurate means to care for their garden and lawn.

We should make careful consideration when applying wood ash to lawn and garden sites. A measured application can be beneficial to increase soil pH. Over applications of wood ash will increase the likelihood of soil related problems.

George W. Hamilton, Extension Educator, Agricultural Resources, University of New Hampshire Cooperative Extension-- Hillsborough County

This information was developed for conditions in the Northeast. Use in other geographical areas may be inappropriate.

The information in this material is for educational purposes. The recommendations contained are based on the best available knowledge at the time of printing. Any reference to commercial products, trade or brand names is for information only, and no endorsement or approval is intended. The Cooperative Extension system does not guarantee or warrant the standard of any product referenced or imply approval of the product to the exclusion of others which also may be available.All agrochemicals/pesticides listed are registered for suggested uses in accordance with federal and Connecticut state laws and regulations as of the date of printing. If the information does not agree with current labeling, follow the label instructions. The label is the law.Warning! Agrochemicals/pesticides are dangerous. Read and follow all instructions and safety precautions on labels. Carefully handle and store agrochemicals/pesticides in originally labeled containers immediately in a safe manner and place. Contact the Connecticut Department of Environmental Protection for current regulations.The user of this information assumes all risks for personal injury or property damage.Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture. Kirklyn M. Kerr, Director, Cooperative Extension System, The University of Connecticut, Storrs. The Connecticut Cooperative Extension System offers its programs to persons regardless of race, color, national origin, sex, age or disability and is an equal opportunity employer.

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