Locust is considered a highly desirable firewood, often ranking among the best available options for home heating. The wood’s reputation stems from its high density, which directly translates to excellent heat output and long-lasting coals. Understanding the specific performance, preparation requirements, and differences between the two main species is helpful for anyone considering using it as a fuel source.
Firewood Performance and Heat Output
The quality of locust firewood, particularly Black Locust (Robinia pseudoacacia), is primarily due to its high density, averaging around 48 pounds per cubic foot. This density means a cord of seasoned locust wood contains a greater mass of burnable material compared to many other hardwoods. Black Locust delivers approximately 27 to 29 million British Thermal Units (BTUs) per cord, comparable to premium fuels like hickory and oak.
When properly seasoned, locust wood produces a slow, steady, and hot fire. This extended burn time is valued for overnight heating, as the dense wood breaks down slowly. It is also recognized for its excellent coaling properties, leaving behind a deep bed of long-lasting, hot embers that can easily reignite a new fire the next morning.
Burning seasoned locust results in minimal smoke and ash production, contributing to a cleaner burn and reduced creosote buildup in chimneys. A characteristic that requires caution is its tendency to throw sparks or “pop” while burning, especially if the wood is not fully seasoned. For this reason, it is best used in enclosed wood stoves or fireplaces with a protective screen.
Processing and Seasoning Requirements
Preparing locust wood for burning involves challenges due to its inherent toughness. The wood’s extreme hardness and often twisted grain structure make it difficult to split manually, frequently requiring mechanical assistance such as a hydraulic splitter. Splitting the wood while it is still green is recommended, as the task becomes even more challenging once the wood has begun to dry and harden.
Locust is naturally resistant to rot and decay, a property that contributes to its longer seasoning time. While its initial moisture content is relatively low for a hardwood, its density means water is trapped tightly within the wood fibers. For optimal burning efficiency, the wood must be seasoned to a moisture content of 20% or less.
Achieving this low moisture level requires a longer period than less dense woods, often demanding 12 to 18 months, and sometimes up to two years in humid environments. The split pieces should be stacked off the ground in a location with good air circulation and sun exposure to facilitate the drying process.
Black Locust vs. Honey Locust
The term “locust firewood” refers to two distinct species: Black Locust (Robinia pseudoacacia) and Honey Locust (Gleditsia triacanthos). Black Locust is considered the superior firewood, possessing a higher density and greater BTU content, around 28.3 million BTUs per cord. This species earns the wood its reputation as a top-tier fuel source.
Honey Locust is also a quality hardwood, offering a high heat output of approximately 26.5 million BTUs per cord, comparable to many oak varieties. It is slightly less dense than Black Locust. A handling consideration for both species is the presence of long, sharp thorns on the branches and trunks, which necessitate careful handling during processing.