Black Locust, How Do I Love Thee, Let Me Count the Ways: Hmm. At Least Seven.
In Belize, it sounds daft, but I used to find myself daydreaming about a tree called madre de cacao (Gliricidia sepium). It was a strapping type of tree: tall, quick-rooting, nitrogen-fixing. While living there, my wife Emma and I were doing a work-trade at a local cacao farm, and we discovered this specie, the “mother of cacao”, and instantly put it to work in our gardens. It made for great living fence posts and produced an abundance of rich mulch material, all the while making the area fertile. What more could a young permaculturist want?
When eventually our time in Belize came to a close, I never thought I’d find a tree quite so alluring, until this year, arriving in North Carolina, when I was introduced to a tree that I’d read about from time to time but had never actually knowingly encountered: The black locust (Robinia pseudoacacia). I’ve only become more enchanted since that first day, when the owner of Snaggy Mountain, Jared, told me how the black locust was the best firewood around. We were talking about coppicing trees, and I asked if the black locust would work. He didn’t know. I decide to do some research: Not only would it work, it came highly recommended, and there was a lot more as well.
Like many a good tree (and weed), black locusts are considered by some as an invasive species, but in defense of my new muse, these people perhaps aren’t seeing the full potential of what is. This tree is an incredibly useful, multi-functional addition to permaculture sites, and while it may require some maintenance to prevent spreading (as did madre de cacao), like any appreciated diamond in the rough, it also has the potential to pay back in dividends for those willing to nurture the beauty that is the black locust.
A big difference between North Carolina and Belize is the climate. In Belize, madre de cacao was appealing because it could be coppiced or pollarded to provide sustainable firewood for cooking, but in North Carolina, the stakes are upped a bit more. In the humid cool winter of these mountains, firewood can be crucial for heating, especially on off-grid homesteads. Not only can be locust be coppiced, but it is also—as Jared pointed out—a dense, hot-burning, long-burning wood. The wood has certain qualities that also help it store for longer than other choices.
In the same breath, black locust wood is so revered as a timber wood, especially for outdoor items like fence posts and decking, that it almost seems a crime to burn it. It’s rot-resistant, so it’s often the chemical-free version of lumber where treated wood might be used. Because it is fast-growing and quick-spreading, it also makes for a sustainable source of wood, as cutting some back is a necessity. Plus, its strength is compared to that of oak, which means it can do some serious framing work.
The often exalted quality—at least amongst permaculture enthusiasts—of being nitrogen-fixing is something that is always worthy of taking note of. Black locusts are nitrogen-fixing over-story trees that commonly reach up to 24 meters high. They can also be coppiced and pollarded for firewood and fence posts, which would mean that larger quantities of nitrogen are released into the soil when the wood is harvested. For the same reasons, they are potentially a great companion plant in food forests, providing fertility and chop-and-drop mulch.
One of the knocks on black locust is that many parts of it are toxic for humans (and horses). The beans, the leaves, the roots are no good for eating, but the flowers are. And, they are absolutely delicious. What’s more is we learned at Jared’s farm that, for those willing to harvest them, there is a market for selling them, that some restaurants will pay high dollar. It’s the same kind of irony as dandelion greens bringing in big dollars in markets: When flowering, black locust flowers are in abundance for free.
Continuing on with the flowers, bees apparently love to forage from the black locust blooms. It’s known to be one of the top trees for honey bees in the US, and the honey produced from black locust pollen is said to be “fruity and fragrant”. A relatively pure locust honey is also high in fructose, nearly clear in color, and that it makes it—like the wood from locust trees—a viable candidate for long-term storage. The black locust was actually exported long ago to Europe, and it has remained a popular honey-producer there.
Chicken of the Woods
Another exciting part of North Carolina has been the wild edible mushrooms. Mushrooms are widely enjoyed or produced in Central America, so to suddenly have them in such abundance and variety is exciting. One of the most beloved wild edible mushrooms here is the “chicken of the woods” (Laetiporus sulphureus), which just so happens to like growing on black locust trees. In fact, like oak, black locust logs have good characteristics for mushroom cultivation; however, there is debate as to whether the toxicity of the tree ruins the mushroom, so this would require some caution.
A common problem here in North Carolina is a late frost, after apple and other fruit trees blossom, and this is known to decimate crops. A potentially good solution for this (my theory) is allowing some black locusts to grow up as over-story trees. They are known to have rather airy foliage, which will allow sunlight in but, hopefully, provide some protection from cld frosts. We used madre de cacao in Belize similarly, only to dapple the sunlight during the hot dry season, so I see real potential in experimenting with black locust to combat frosts.
Eight, Nine, Ten…So Many More!
Inevitably, as research has proven time and time again, it only takes a fledging interest in a tree or plant, and suddenly, it can be seen in a whole new light, and another, and another. The more I started pondering the potential of using black locust, the more I discovered how it can be used. Some use it for fodder (not for horses!). It is known as a dynamic accumulator. It is obviously, like many quick-growing legumes, a pioneer plant for degraded landscapes, which is why it has a weedy reputation. It’s fantastic for erosion control. It provides an abundance of biomass. It is an adaptable grower, tolerating soils with pH levels down to 5.1 and up to 8.5 and working in climates ranging from USDA 3 to 9. There are only a couple of bugs that bother it. It’s a tolerant of juglone, a growth inhibitor released by black walnut (common here), which makes it a potential buffer tree. It’s a great shelter for small animals, and hummingbirds love it. For that matter, I think I do, too.
Well, the love story has only just begun, and I’ll admit that everyone is smitten at the beginning of a relationship. But, I can just really see this one going somewhere. I know some folks might only see the invasiveness and toxicity, but there’s more to the black locust. I’m sure of it. Let’s just hope I’m burning it, and it’s not burning me.
Header Image: Black Locust Label (Wendy Cutler)