As the leaves dazzle the woodlands, the sounds of chain saws and log splitters, become as numerous as the migrating flocks of birds. It’s time to get ready. Burning firewood is an important source of heat for many northern families; with a good wood stove, there’s a warm house and plenty of wood ashes to clean out of the stove. The ashes can be valuable for homeowners who pay attention.
On average, it is estimated that a chord of wood ( 4 feet x 4feet x 8 feet) will produce approximately 20 pounds of wood ash; and on the average, most sources will claim that is about a five gallon bucket filled to the top.
The wood ash amounts will vary according to the type of wood being burned, and the type of stove being used and how often. But regardless, the end result of all the sawing, splitting, hauling and stacking in the fall, is a lot of wood ash. The wood ashes can, however, be a valuable landscape or garden resource, but the “devil” is in the details.
Know Your Wood
Wood ash does contain some valuable nutrients for the garden or lawn. In general, the largest component found in wood ash is calcium carbonate (lime) which helps to raise the soil pH. Potash is also found in wood ash and on average is listed as the next most common component at 10% followed by 1% phosphate. There can also be trace amounts of iron, manganese, boron, copper and zinc.
The amount of valuable nutrients, however, depends on what type of wood is being burned. It is generally agreed the hardwoods produce the greater amounts of nutrients. Hardwoods, such as oak, maple, elm and beech have one third or more of the valuable nutrients. If your buying your wood, and plan on using the ashes, it is best to understand and know what specie(s) you are buying.
Know Your Ashes
Naturally, toxic chemicals could be present in the wood ash if treated lumber or coal was burned or if plastic or any other non-wood product was used in the stove. Be careful when burning cardboard; the glue contains boron which, in excess, can stunt plant growth. Non-wood products should not be burned if the ashes are to be used, particularly in the garden
The best time to apply the ashes to the soil is in the early spring and it is best to work them into the soil. During the winter months, the ashes should be safely stored and kept dry. Always store the ashes in metal buckets with tight fitting lids in a safe area, away from the home. Fire Departments usually have enough work to do in the winter months. Keep the wood ashes dry. Once the ashes get wet, they lose the valuable nutrients.
Know Your Soil
Soil tests are the key to a successful application of wood ash. The essential reading in determining the application rate is the soil pH. If the pH is 7 or greater, the soil will not benefit from an application. In general, 10 to 15 pounds of ash can be used per 1,000 square feet, depending on the outcome of the soil test Ashes can also be used effectively in the home compost pile and can be sprinkled on top of each layer as the pile is built.
In general, vegetables will enjoy an application of wood ashes depending on the soil test. There is one exception; do not use the ashes where potatoes will be grown because of the possibility of potato scab. Tomatoes, however, seem to enjoy an application of wood ash.
Keep the wood ashes away from acid loving plants such as azaleas, camellias, conifers and junipers. But keep the ashes to apply ashes around fruit trees, deciduous trees and shrubs.