The tragic Christmas Day story the house that burned and killed three children and their grandparents is an unfortunate reminder that you must be careful when burning wood even beyond the hot flaming stage. The fire was caused by the improper disposal of wood ashes, which according to statistics, cause around 10,000 house fires a year.
Wood heat can be a very satisfying heat source. It’s a renewable fuel, available locally and not through OPEC, pleasing to stare into, and particularly satisfying to back your rear end up to and enjoy the warmth. I burn wood myself and enjoy it very much. But a maintenance chore created by burning wood is the occasional removal of the ashes from the stove or fireplace. A cord of hardwood firewood produces around 60 pounds of ashes that must be disposed of. And there is where folks get in trouble. Wood ash is a very good insulator, and while the outside of a pile of freshly removed ashes may look and feel cold, it often has hot coals mixed in that produce no smoke or glow, but can retain enough heat to ignite (given time) flammable materials they make contact with. So with this in mind, pay heed to the following guidelines on handling and disposing wood ashes.
Do not place the ashes in a paper or plastic bag, cardboard box, or similar container. Don’t just dump fresh ashes at the edge of the yard. We annually have wildfires that were caused by hot ashes igniting nearby grass or leaves. The best routine for ash disposal is to first place the ashes in a metal container with a tight lid, and then place the container in a safe place for several days until the coals go cold. Do not place the metal container on your deck, in your garage, or any location that will allow heat to transfer from those hot coals to nearby flammable items (like the deck and house). Store the container outside and away from any combustible materials.
Once the ashes are dead cold, you may then dispose of them, hopefully in a useful manner. Wood ash can be useful around the garden as a soil amendment. It contains 1-2% phosphorus, 7-10% potassium, plus micronutrients such as iron, manganese, boron, copper, and zinc. The largest component of ash is calcium carbonate, making it useful as a liming agent to neutralize acidic soil. One rule of thumb for soils such as ours is to use 1 gallon of ashes per square yard of garden or lawn per year. It’s a good idea to have your soil tested every couple of years to be sure you’re not overdoing it and making the soil too alkaline. If you store some ash until spring, it can be used for insect control. Spreading a circle of wood ash around the base of plants has been used as a deterrent for maggots, cutworms, cucumber beetles, squash borers, spider mites, potato bugs, and slugs. If you store ash for later use, protect it from rain to prevent nutrients from leaching away. But remember, always make sure the ashes are cold-cold before placing them on the ground.