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Is Locust Good Firewood? Black Locust Is About the Best

Black locust tops almost every BTU table at around 29 million a cord, burns with little smoke and stores for years without rotting.

By Zakaria 2 min read Save to Pinterest — opens Pinterest in a new tab
A heap of freshly split hardwood logs showing pale cut faces
Photo: manfredrichter, Pixabay Content License, via Pixabay
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Black locust is about the best there is. Roughly 29 million BTU a cord, a long hot burn, very little smoke or spark, and it stores for years without rotting. Honey locust is a different tree and slightly behind it.

Black locust against the rest

This table answers the question on its own
WoodMillion BTU / cordSmokeStores
Black locust~28–29Very littleYears
Hickory~27–28LittleWell
Oak~27–28LittleWell
Beech~27–28LittleRots in the round
Honey locust~26LittleModerate
Ash~24LittleWell

Two different trees

Black locust vs honey locust

Black locust (Robinia pseudoacacia) — denser, hotter, famously rot-resistant, the one used for fence posts. Honey locust (Gleditsia triacanthos) — a good fuel at ~26 million BTU with good coals, but less durable stacked, and wild trees carry long branching thorns on the trunk that cause serious puncture wounds. Take both; pay for black locust.

Seasoning and splitting

  1. Split it green. Dense, stringy, interlocked fibres hold a split together even after the maul has passed through — and it gets worse as it dries.
  2. Twisted trunk sections go to the splitter. Black locust often grows with a spiral.
  3. Stack off the ground, single rows, top covered only.
  4. 12–18 months. Its rot resistance means a slow drying season costs you far less than it would with beech or birch.
  5. Meter before burning — under 20%, as with any wood.

Why it stores so well

The same extractives that make black locust posts last decades in the ground stop a woodpile degrading. A locust stack that has sat two years longer than planned is still good fuel, which is not true of most hardwoods.

Handling it safely

The wood is fine to burn. Two things to know: bark, leaves and seeds are toxic if eaten, which matters around livestock rather than around a fire; and young black locust and most honey locust carry thorns. Gloves, and watch where you put your hands in the stack.

Common questions

Is locust good firewood?

Black locust is about the best firewood available in North America and most of Europe. It sits near the top of every BTU table at roughly 28 to 29 million per cord, burns long and hot with very little smoke or spark, and leaves an excellent bed of coals. It is also naturally rot-resistant, so split stacks keep for years rather than degrading. Honey locust is a different tree and a slightly lesser but still very good fuel at around 26 million BTU.

What is the difference between black locust and honey locust as firewood?

Black locust is denser, hotter and far more rot-resistant, and it is the one that tops firewood charts. Honey locust burns well too at about 26 million BTU per cord with good coals, but it is less durable in storage and the thorns on the trunk and branches of wild honey locust are genuinely dangerous to handle. Both are worth taking; black locust is worth paying for.

How long does locust take to season?

Twelve to eighteen months is typical, which is faster than oak despite similar density, because locust does not hold water the way oak does. Split it, stack it off the ground in single rows with the ends open to the wind, and cover only the top. Its rot resistance means a locust stack tolerates a slow drying season far better than beech or birch would.

Is locust hard to split?

Yes, and it is the main complaint about it. The wood is dense and often has stringy, interlocked fibres that hold a split together even after the maul has gone through. It is noticeably easier green than dry, so split it early. Black locust also frequently grows with a twisted trunk, and those sections are a hydraulic splitter job.

Does locust spark or smoke?

Very little of either, which is part of why it is so well regarded. Seasoned black locust burns with a steady, almost smokeless flame and throws few embers, making it one of the better choices for an open fire pit as well as a stove. The caveat that applies to every wood still holds: burn it wet and it will smoke and lay down creosote like anything else.

Is locust safe to burn?

Yes. The wood is not toxic to burn and black locust is widely used as firewood and as fence posts. Note that the bark, leaves and seeds of black locust are toxic if eaten, which matters around livestock rather than around a fire, and that the thorns on honey locust and on young black locust can cause nasty puncture wounds, so handle and stack it with gloves.

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