Willow wood is often chosen as firewood because the tree is readily available or needs to be cleared. The direct answer to whether willow wood burns well is nuanced: it ignites easily and burns quickly, but it is considered a poor choice compared to denser woods used for sustained heat. Willow is technically classified as a hardwood because it is a broadleaf tree, but its physical properties cause it to behave much like a low-density softwood. This characteristic means it can make a quick, hot flame ideal for kindling or starting a fire, though it will not provide the long-lasting heat needed for overnight burning or primary home heating.
Density and Heat Output
Willow wood is categorized by its low density, which is the primary factor limiting its effectiveness as a long-burning fuel. At a standard moisture content of 12%, willow wood is one of the lightest available, weighing approximately 27 pounds per cubic foot. This low specific gravity directly translates to a lower heat output per volume of wood compared to denser species.
Willow typically produces around 17.6 million BTUs per cord. By comparison, dense woods like white oak can yield over 25 million BTUs per cord, demonstrating the significant difference in energy content. This lower density means willow burns fast and hot initially, but it does not produce a deep, long-lasting bed of coals. Consequently, frequent reloading is required to maintain a consistent temperature, making it inefficient for prolonged heating.
Proper Preparation for Burning
The high moisture content of green willow wood makes proper seasoning a necessary step before burning. Willow trees naturally thrive in moist environments, causing the wood to retain a large amount of water, sometimes exceeding 50% of its weight when freshly cut. Burning wood with high moisture content wastes energy because a large portion of the heat is consumed boiling off the retained water.
To be considered usable fuel, willow wood must be seasoned until its moisture content drops below 20%, with an ideal range being under 15%. Due to its high initial water level, willow often requires a longer drying period than many other woods, frequently taking 12 to 24 months depending on the climate and storage conditions. Splitting the wood into smaller pieces and stacking it off the ground with a cover facilitates air circulation. This prevents the wood from absorbing moisture or rotting before it is dry enough to burn efficiently.
Smoke and Residue Characteristics
Unseasoned willow wood produces considerable smoke during combustion. This excessive smoke is a sign of incomplete burning and accelerates the buildup of creosote, a flammable residue, inside the chimney or flue. Even when well-dried, willow carries a higher creosote risk than many denser hardwoods.
The remnants of burning willow are characterized by a light, fluffy ash that accumulates quickly in the firebox. This characteristic means that more frequent cleaning is required to prevent the ash bed from smothering the flames. While willow generally burns without heavy sparking, its fast, hot flash is useful for quickly establishing a fire before switching to a slower-burning fuel.