Black Locust isn’t as popular as Ash or Oak wood for fires, so not many people know about it nor its qualities as a firewood. However, for those who are familiar and have used it, it’s often considered as the best firewood.
Black Locust, a variety of Locust trees, burns slowly and very strongly, which is the main reason why this wood is a favorite amongst those who have tried many different kinds. It also has no smell and produces very little smoke, two other big benefits that make this wood one of the best.
This fast growing tree is native to the southeastern U.S., but it grows pretty consistently and commonly throughout all the U.S. and can be found in many parts of the world, including Europe, Central Asia, Northern Africa, and China.
Black Locust Firewood Characteristics
Here’s a snapshot of the main characteristics of the Black Locust as firewood. Throughout this article I’ll explain what each of these categories describes and what they mean about the quality of Black Locust as a firewood.
- BTU: 27.5 to 29.8
- Weight: 4650 wet 3900 dry
- Seasoning Time: 1 year
- Resin / Sap Content: Low to medium
- Splitting Difficulty: easy
- Smoke: low to medium
- Smell: slight, pleasant
Burn (BTU)
One of the main reasons why Black Locust firewood is regarded as the best is because it has one of the highest BTU ratings compared to other kinds of firewood. First, let me explain what BTU means.
BTU stands for British Thermal Units and is just a unit of measurement for heat. BTU is measured as the amount of heat it takes to raise one pound of water by one degree Fahrenheit. BTU is the standard unit of measurement for firewood, so it’s likely that you’ll see this unit to describe many kinds of firewood and even other heating fuels like gasses.
To give you some perspective, here are the BTU ratings for the most popular kinds of firewood:
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- Green Ash: 20
- Maple: 25
- Oak: 26
- Black Locust: 30
You can see that Black Locust has the highest BTU rating compared to common alternatives. There’s only one other kind of wood that has such a high BTU rating and that’s Osage-Orange, but this kind of wood doesn’t grow in the U.S. and is therefore very rare to find.
All that you need to know about this very high BTU rating is that it means Black Locust creates a HOT fire. This firewood is known to put off extremely high heat, making it perfect for heating the house or for fuel.
In fact, the fire is so strong that you need to be careful if you’re using Black Locust firewood for a wood-fired stove. The fire is so intense that it could likely burn what you’re cooking, so if you’re using Black Locust you want to mix it with other types of firewood to keep the fire mild.
Such a high rating also means that the fire will burn for a long time- essentially Black Locust firewood just burns very well and powerfully. This is because the tree grows with a very dense trunk, so the wood is compact and holds a fire well. This also means it creates very strong coals that rest at the bottom of the fire.
Because of this, Black Locust firewood is great for heating your home overnight if you have a firepit for internal heating. Since the coals are so hot, you can easily add more wood in the morning to keep the fire going.
Although Black Locust burns so strongly, it’s not great to use as kindling. Kindling just refers to the tiny pieces of wood and plant material that you use to start a fire. Even very tiny shreds of Black Locust won’t work well for starting a fire because the wood is so dense.
Seasoning
“Seasoning” firewood is basically just the process of drying it so it’s prepared for the fire. If you try to put freshly cut wood in a fire, it will still have too much moisture and will burn very poorly. So, regardless of the kind of wood you’re using, it’s important to dry or “season” it.
The minimum recommended time for seasoning is 6 to 8 months, any less than this will leave the wood still a bit too moist. The ideal time is about one year, because a full year of drying is definitely enough time to ensure there’s no more moisture to prevent a strong fire.
Those who have used Black Locust many times and are familiar with this wood say that if you have the time to let it dry, it’s recommended to dry it for up to 2 to 3 years. However, drying it for this long isn’t necessary and it will burn fine with just one year or drying.
When Black Locust wood is cut fresh it has about 26-28% moisture because of the sap and resin inside the tree. With any type of firewood, you want the moisture of the wood to go down to about 20%.
Speeding Up Drying
There are also a few ways you can speed up the process so that the wood will dry faster, if you don’t have as much wood or time available. Increasing the airflow between the wood pieces is the best way to help them dry faster, but you don’t exactly want to just leave them out in the elements.
The first thing you can do is to stack the wood pieces off the ground so the moisture from the ground isn’t soaked into the wood. If you have wooden pallets or a firewood rack where you can place them, that would be perfect!
You can also stack them in an alternating pattern so that air can come between. If you cram all the pieces in a tight space, the moisture will stay locked in and they will take longer to dry. Stack them so there’s an open path for airflow to ensure all the pieces dry fairly evenly.
One last thing to do is cover the stack of wood to protect from rain or snow. You can do this best with a tarp over the stack or creating a stack under a covered area like a shed.
Firewood Smell
Another reason why Black Locust is a favorable firewood is that it has very little smell when burning. Unlike many popular firewood types, Black Locust has a neutral smell that is almost non-existent.
This neutral smell is another reason why Black Locust is a preferred firewood for heating homes. Whether you have a central heating stove or a living room fireplace, you can use this firewood to fuel your fire without leaving a smell permeating throughout the house.
Smoke
Another great advantage of Black Locust wood is that, when properly seasoned, it produces very little smoke. Low smoke makes it a great wood for strong fires both indoors and outdoors in a fire pit.
One major issue to consider when choosing a firewood to burn indoors is creosote buildup. Creosote is a resin that accumulates in your chimney from sap particles that escape with the smoke and are carried up into the chimney.
Even if you have a liner for your chimney, if you’re using wood that’s too wet or produces a lot of smoke, you’ll have more buildup of these waxy particles in your chimney. This can create serious health risks by polluting the air in your home.
If there’s too much buildup of creosote, your chimney could also get damaged. It’s important to have your chimney thoroughly cleaned to make sure this buildup is taken out and doesn’t destroy your chimney’s structure. This is another reason why it’s so important to season the wood for long enough.
As noted above, with what little smoke the fire does produce, it doesn’t have any smell. It’s also good to know that the smoke is non-toxic, another reason why Black Locust is great for burning indoors and heating your home.
You should keep in mind that because this wood doesn’t produce very much smoke, it’s not suitable for smoking meats. Other woods like Hickory or Mesquite produce more and stronger smoke that will actually create the smoked flavor.
Cutting and Splitting
Any firewood enthusiast that has experience with Black Locust wood will tell you that the greatest drawback to this powerful firewood is the difficulty with splitting. Black Locust is a dense type of tree, so the cutting and splitting process is labor-intensive.
First off, the grains of the tree are very tight, which just means that the branches are very compact and have more resistance to cutting. These trees also have many branches, which requires extra work to cut off the smaller branches and twigs and work around the knots.
The best time to cut down Black Locust trees is in late winter to early spring, as this is when the wood will be the driest with the least sap. This will also make the cutting and splitting process easier.
The branches of the Black Locust trees have spikes along them, so it’s important to wear good quality leather or latex dipped gloves to protect yourself. Also stay mindful of this as you’re walking through a forest of Black Locust.
This tree grows rapidly and is even considered invasive in many regions (particularly into crop fields) so cutting the trees down is a way to control the intense growth while also gathering firewood for yourself!
Black Locust trees grow in colonies, so they’re always found in clusters or large forests. Each colony has a mother tree that sends nutrients to the others, so make sure not to cut this down as you’ll then take out the whole forest!
Once you’ve chopped enough pieces for your home heating needs, make sure to set them aside to dry. After they’ve been seasoned long enough, you can split them further to make smaller pieces.
One more reason that Black Locust is considered difficult to split is that the wood, because it’s so dense, is very heavy. This means you need to strike harder and cut deeper, and the wood is heavier to carry. But, thankfully, this firewood makes up for its long preparation time by burning intensely for a long time.
About the Tree
Here’s some additional information about the Black Locust tree so you can learn to identify it and learn the different types of Locust trees. Although there are various kinds of Locust trees, they all have some similarities.
Locust trees are fast growing hardwood trees with spikes that grow in pairs on the branches. They usually live for around 100 years and can grow up to 170 feet tall!
Locust trees have roots that are particularly resistant to rot, a strong factor in why they grow so quickly and strongly. Also, because these trees grow in colonies and have the support of each other, they grow very well and can spread rapidly.
Close photo of a Black Locust tree. Black_locust,_Isham_Park / Beyond My Ken / CC BY SA 4.0
In fact, they grow so fervorously that it’s essentially necessary to cut them down to keep the growth under control. These trees don’t hold form very easily, so if you try to prune them they will just continue growing crazily!
Locust trees have some variation in their looks, but in general they have reddish-black bark with large, diamond shaped grooves. Their “fruit” is a little seed pod that is toxic to humans and other animals.
However, their gorgeous white flowers are edible! Many people like to use the drooping white flowers in jellies, honey, or cook them into fritters or baked goods.
Let’s now go over a few of the different kinds of Locust trees you might come across.
Picture of a fully grown Honey Locust tree, where you can see the lighter yellow-orange leaves. Gleditsia_triacanthos_Maryhill_Museum_01 / Kevmin / CC BY SA 4.0
Honey Locust
The Honey Locust is the second most popular kind of Locust tree and the next most likely kind of Locust firewood you might come across.
It has many of the same features as the Black Locust regarding both for the tree and the firewood, with just two main differences. Honey Locust firewood isn’t as hot (although it still produces a nice fire), and it’s easier to split!
It does have a more noticeable smell than the Black Locust. While it’s still very subtle, it has a slightly sweet smell- hence the name Honey Locust.
Frisia Locust
The Frisia is very similar to Black Locust, just differing by having tougher wood. The Frisia Locust grows in colder climates, so it has denser wood that becomes tight with the cold air.
Inermis Locust
The Inermis Locust is a smaller, almost dwarf variety of the Locust trees. It only grows to about 20 feet tall (compared to Black Locusts at over 130 feet) and has a compact shape. This Locust has a rounder shape with an umbrella top.
Flowers on the Purple Robe Locust in the sun.
Purple Robe Locust
This is a more common variety of Locust, distinguishable by its brighter colors. The Purple Robe has a darker, bronze and reddish bark with bright pink flowers that make this tree a favorable landscaping option.
This variety is also a smaller size, only reaching around 40 feet in height and having a compact branch structure. This variety also has a slightly shorter life span, around 130 years.
Pyramidalis Locust
This variety of Locust is much more stout, reaching only 40 feet in height but with a trunk up to 15 feet in diameter! However, the bark and flowers of this Locust are the same as the Black Locust variety.
Tortusa Locust
The Tortusa Locust is important to know because it’s the only variety of Locust tree that doesn’t create good firewood. While the Black Locust is arguably the best firewood, all the Locust varieties except Tortusa create very nice firewood.
This tree is similar to the Pyramidalis, short in height and large in diameter and width. The Torusa has contorted branches that bend and twist in a funky way.
Umbraculifera Locust
Lastly, is the Umbraculifera Locust, a small and stout Locust tree that, as the name implies, has an umbrella shaped top. This tree is native to and more commonly found in Europe, so it’s likely you won’t come across this variety in the U.S.
Black Locust as Firewood
In summary, yes, Black Locust is a fantastic firewood. This is because it produces an extremely hot fire that burns for a very long time. Additionally, it hardly creates any smoke and the fire doesn’t have any smell to it, both of these reasons making it even more favorable for burning indoors for heating.
Also, because Black Locust burns for such a long time, it produces very hot coals under the fire that will hold in heat for a long time. This is partially why the fire burns for so long and can remain so hot and coals also allow you to continue the fire the next day.
For all these reasons, Black Locust is considered one of the best firewoods and is particularly favored for heating your house because it produces so much warmth and can continue burning all night long.
The one major drawback to Black Locust firewood is that it’s very tough and hard to split, so if you want to cut and split it yourself, you’ll really need a high quality axe and some serious strength.
Keep in mind that Black Locust grows incredibly quickly, without hesitation, and is very hard to control. So, if you’re considering planting some to have access to firewood trees on your property, you will need to cut the trees often or do large cleaning to keep the tree growth in check.
Bottom line, if you have access to Black Locust firewood either through a local store or forest, it will create a strong and powerful fire that will burn for hours, great for your home or an outdoor fire pit!
