Black Locust
For the rare hardwood that rivals hickory's BTU while splitting easier -- black locust is a top-tier, if less commonly available, firewood choice.
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Why this fits you
- You have access to black locust and want top-tier BTU without hickory's splitting difficulty.
- Long, hot, efficient burns matter more than easy availability.
- You're willing to source a less common species.
Black locust burns around 26-29 million BTU per cord, rivaling hickory, but splits more predictably along straighter grain. It's also notably rot-resistant, which is why it's popular for fence posts as well as firewood. The main limitation is availability -- it's a regionally distributed tree, not sold everywhere the way oak or ash typically are.
Among the hottest woods
Black locust is one of the densest firewoods in North America. It is typically listed at about 26 to 28 million BTU per cord, comparable to or higher than hickory and ahead of most oaks. It burns long, hot and with little smoke, and leaves long-lasting coals. Many people regard it as the best firewood available in the eastern United States.
Seasoning and splitting
Locust dries more quickly than oak despite its density, and is often ready within a year. It splits best when green and can be very hard to split when dry, so split it early. The wood is also extremely rot-resistant, which is why it is used for fence posts and decking. Firewood stacks can sit outside for a long time without decaying.
Burning cautions
Because it burns very hot, black locust can overheat some stoves and, if loaded heavily in a small firebox, may shorten the life of firebricks or baffles. Mix it with lighter woods, and follow the stove maker's guidance on loading. It can be slow to catch, so start the fire with kindling or a lighter wood.
Availability and cost
Black locust grows quickly and spreads readily, and it is considered invasive in some regions, so it is often available from landowners who want it cleared. It has thorns, which makes handling and processing more irritating. Check with a local tree service or a sawmill for supply.
When to choose something else
If you have a small or lightweight stove, a less dense wood is easier to manage. Choose black locust for maximum heat and long burns if you can handle splitting it early and your stove can take it.
Stove loads and splitting
Because black locust is so dense, split pieces smaller than you would other woods so the stove can ignite them, and load fewer pieces at a time to avoid overheating. Wear gloves, since thorns on small branches and bark are sharp. If you cut your own, split green, and let it dry in a sunny, windy stack.
How it compares
| Species | BTU/cord (millions) | Season time |
|---|---|---|
| Oak | 24-29 | 1-2 years |
| Hickory | 27-30 | 1-2 years |
| Ash | 20-24 | 6-12 months |
| Sugar Maple | 21-24 | 6-12 months |
| White Pine (softwood) | 15-17 | 3-6 months |
| Black Locust | 26-29 | 1-2 years |
| Red Maple | 18-20 | 6-12 months |
| Black Cherry | 20-21 | 6-12 months |
Buying checklist
- Confirm local availability before planning around it -- distribution is regional
- Season similarly to oak/hickory, 1-2 years for best results
- Excellent choice if you already have access to it on your property
Run the numbers
Frequently asked questions
Why isn't black locust more widely available as firewood?
It's a regionally distributed species in North America, more common in some areas than others, so supply depends heavily on your specific location.
Is black locust good for anything besides firewood?
Yes -- its rot resistance makes it a popular choice for fence posts and outdoor lumber, often as valuable for that use as for burning.
Does black locust season as slowly as oak?
Similarly, yes -- expect 1-2 years for full seasoning given its density, though it's noted for splitting more easily than hickory along the way.
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