| Oct 22, 2009

Back to HomeMaster Gardeners - October 22, 2009 Wood Ashes: Use in Your Graden with careby Ankaret Dean, Lanark County Master Gardeners

At this time of the year thoughts are turning to firing up our stoves. 

Many of us using wood fires to heat the house have the same problem. What to do with the wood ashes? There are many answers to this and after searching I will try and gather up the pertinent facts.

Firstly, for every cord of wood, depend-ing on the efficiency of the combustion and type of wood, the yield will be about twenty pounds of ashes or equivalent of one five-gallon pail. In pioneer times wood ashes were treasured for the production of lye, (see below) and fertilizer, but now it’s main use seems for spreading on slippery ice!

Wood ashes contain about 1% phosphorous, 5% potassium and small amounts of other elements that our plants need to bloom and establish a strong root system. The potassium combines with soil water to form an alkaline substance commonly known as ‘lye’, or potassium hydroxide. It is this substance that reacts with the soil and raises the soil pH, and it is this factor that can affect the soil in our gardens. If your soil pH is above 7.0 or higher, you should not use any wood ash on your soil. For lower readings, wood ash is an alternative to using ground limestone. The av-erage ash is equivalent to a 0-1-2 reading.

Other factors regarding the use of wood ashes include the unlikely possibility of trace metals in the ash which could be transferred to your vegetables and find their way into your food.

The ashes may be spread on the ground, preferably on top of snow. This way they will be diluted as they enter the soil and will not burn growing plant material or germinating seeds. Alternatively they can be spread over the ground before tilling in the spring.

Estimated quantity to spread on the ground is a 5-gallon pail over 1000 square feet. Wood ash should never be applied to an area where potatoes are grown, (can cause scab) or near acid loving plants such as azaleas, rhododendrons etc.

Care should be used in handling wood ash as it is a very fine powder; eye protection, a mask and gloves are recommended. Avoid spreading on windy days.

Ash should be stored in a metal container with a lid and kept dry. Leaving it in piles on the ground can cause excessive build-up of chemicals in the soil.

There are some interesting tips regarding the use of wood ash. It can be used to sprinkle around the base of plants, or around the garden to avert insect and slug damage.

A small handful rubbed on a pet’s coat will diminish the smell of skunk. Place a quarter cup of ash in the hole while planting tomatoes; they are acid loving plants.

Use with a little water to clean fireplace doors, similarly ash can be made into a paste and used to clean silver.

A handful of ashes sprinkled over the com-post heap will enrich the compost.

In conclusion, perhaps we should appre-ciate the piles of wood ash and use it as a valuable fertilizer, but with great care. For gardening information, call Ankaret Dean at 613-278-1203.

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