(originally published August 2008, updated February 2010)

Depending on where you live, a wood heater can be a *relatively* earth friendly option for heating (see my article on wood heaters and buying firewood) and quite economical; particularly if you’re fortunate enough to have easy access to a supply of wood.

The ashes left behind from a wood fire are also a valuable and versatile by-product – don’t just throw them away indiscriminately; here’s some great uses for your ash! Per usual, exercise appropriate caution, spot test etc. etc. etc. :).

Fire helper

Lumps of charcoal shouldn’t be removed from your fireplace if possible, just the ash – the charcoal will help kick along your next fire and get it cranking out decent heat far faster than if a fire is just started with wood alone. You could also save it and use it for summer barbecues, rather than using some of the commercial products that sometimes have toxic chemicals added (see my related article on greener charcoal).

Filter

Left over charcoal (the black chunks, not the grey/white ash) can be pounded with a hammer and then ground into to a fine powder with a mortar and pestle or blender. This can then be used as a filter medium. Note that it’s not quite the same/effective as activated charcoal that you buy, so don’t rely on it for filtering drinking water.

Pest deterrent

Sprinkle the ash around the border of garden beds to repel snails and slugs. This will need to be applied after rain.

Ice

Wood ash can be used as an anti/de-icing agent – a little more environmentally friendly than salt or other chemicals used these days

Making lye

Lye is used in the production of soap and biodiesel – white ash produced by burning hardwood is best for this purpose. Learn how to make Lye water here.

Compost

Add a dusting of wood ash to each layer of your compost heap as you’re building it up.

Fertilizer

Ash contains potash (potassium carbonate), phosphate, iron, manganese, boron, copper and zinc and can be quite beneficial as a natural fertilizer… sometimes. Wood ash increases the pH or alkalinity of soil, so use sparingly. I made the mistake of applying a stack of it in an area full of limestone – and guess what else is in ash – lime (calcium oxide). It wasn’t the smartest move and I don’t think anything will be growing there for a while. Black charcoal is a little different in that it has a much higher ratio of carbon – so this can be used more liberally.

Dehumidifying

Lumps of charcoal placed in a can punched with holes can help reduce moisture in areas such as closets, basements, under sinks etc.

Cleaning

Dip a damp rag into ash and use to clean silverware, brass and glass. Ash added to a scourer can also give your scouring a bit more oomph.

If you do intend on using wood ash and carbon, be sure not to throw icky bits such as plastics, cigarette butts and such (which you shouldn’t do anyway) into your wood heater or fireplace as it can contaminate it. Ash should be stored in a metal container with a lid. Of course, you should also wait for it to cool before using for any of the above purposes :)

Know of any other uses for wood ashes? Please share your ideas below.