Black Locust: A Tree with Many Uses
In early October this past year, a devoted group of foresters, farmers, extension educations, students, and others gathered at the USDA Plant Materials Center in Big Flats, NY to discuss a common, yet underappreciated tree that has great potential for farms across the Northeast: Black Locust (Robinia pseudoacacia).
Steve Gabriel / Cornell Small Farms Program. Stand of black locust trees.
This tree, which has often been given a bad name for it’s opportunistic rapid growth and robust thorns, is said to be native originally to the Appalachian Mountain range, though it has become naturalized throughout the United States, southern Canada, and even parts of Europe and Asia. The species is incredibly adaptive, growing in many elevations, microclimates, and soil types.
While some have named it an “invasive” tree given its rapid growth and willingness to spread by seed and root suckering, others see these characteristics as advantageous, if only populations are properly managed to harness these qualities. Make no mistake, locust is not a tree to plant and walk away from. It is best when incorporated into managed activities on the farm, of which there are a remarkable array of options and benefits, including:
- Because it fixes nitrogen from the atmosphere, the trees grow incredibly fast (3 – 4 feet in a season) and can quickly become windbreaks, shelterbelts, and shade and shelter for animals in silvopasture grazing systems.
- The nutritional value of the leaves is similar to alfalfa, making it a valuable feed for ruminant livestock. Some sources claim excessive consumption can lead to toxicity, but many farmers have found their animals naturally limit their intake. (horses excepted)
- The tree has been used to support nutrition in other crops, from grains to other trees. Research has shown increases in nitrogen in barley grain crops interplanted with locust, and black walnuts interplanted with locust as “nurse” trees were shown to rapidly increase their growth.
- The flowers are important sources of food for honeybees. In Hungary, Black Locust is the basis of commercial honey production.
- The high-density wood is the most rot resistant wood we can grow in our climate, making it an ideal material for fenceposts, hope poles, outdoor furniture, decks, and other projects that require weatherproof materials.
- It’s BTU rating is among the highest, making it an excellent firewood in both heat value and coaling ability. At our last house, we actually ruined a woodstove by burning too much locust, which gets extremely hot.
young black locust tree. Photo from Wikimedia
If anything, Black locust is almost too good at what is does. All theses attributes have resulted in an extraordinarily high demand; both sellers of locust poles and lumber, as well as those in the nursery trade at the meeting reported not even coming close to meeting the demand for their products. There is a lot of room in the market for more farmers to grow, harvest, and sell black locust products in many parts of the region.
The challenge? Some states prohibit importing, selling, or trading Black Locust, including Massachusetts and it is restricted in Minnesota, Michigan, and New York. This is not necessarily a complete list – check with your state regulators before deciding how to proceed. Each state has it’s own specific regulations.
In New York, a regulated plant cannot be knowingly introduced into a location where it isn’t already present. It’s hard to say if there is such a place in New York, and likely not in any location where farming traditionally occurred, since the tree has a long history of value to both Native Americans and colonizer settler farmers around the state. In any case, in New York the trees can be purchased, sold, propagated and transported legally. Nursery’s are required to attached a disclaimed to any material they sell.
Assuming you are clear to work with Black Locust, it’s important to consider the genetic stock you source trees from, especially if your goal is to grow straight poles or trees that can be milled for lumber. Locust is incredibly crooked in its “natural” form, and so seed selection, and sometimes pruning, is a critical factor for success. Ironically, the Hungarians identified the awesomeness of Black locust a long time ago (1700s), deciding to intentionally import seeds and engage in an intensive breeding program. As a result, some of the best stock today comes from Eastern Europe, and nearly 20% of the forests in Hungary are comprised of Black Locust.
Propagation of new trees is best achieved by either seed, or root cuttings. Of course, seed will express variety in the resulting genetic profile, whereas root cuttings will be clones of the parent tree. To grow from seed, the thick coat must first be broken, most often by soaking in a pot of boiling water for 12 – 24 hours. Root cuttings can be taken by finding a good flare in the tree, and digging up roots at least thumb thickness. Roots are cut into 2” sections and planted in a potting mix or prepared seed bed.
While the tree is suitable for a wide range of sites, avoid extremely heavy clay and soils with excessive water moisture (standing water). Soil prep can be minimal, as the trees can often compete and overtake other competitors quite easily. Protection from deer or other potential pests is critical during the establishment period, usually the first one to three years.
Black locust has just a few pests of concern, and a little observation and vigilance goes a long way. The health and vigor of the trees are important defenses against devastation, as research has shown that good growing conditions are more important than genetic resistance.
Brett Chedzoy / CCE. Black locust logs.
The most common pest is the Locust borer (Megacyllene robiniae) which most often attacks living, stressed trees, causing extensive damage to the quality of the wood. Identifying and removing infected trees can go a long way. It’s critical get to know the lifecycle of the pest. The other is main pest is the leaf miner (Odontota dorsalis), which attacks the tree in spring, turning the leaves brown by mid-summer or early fall. Overall tree growth can be impacted, but usually not seriously.
One of the most exciting conversations at the meeting was around the good economics for Black Locust, which can be summarized as demand far outstripping the supply. A recent blossoming of interest in natural and sustainable materials for garden and fence posts, coupled with a boom in the hop production industry in the Northeast mean that black locust polewood (which requires only harvesting and cutting to length) can alone be a valuable product from the farm woodlot. Larger, straight trees can also be milled and either sold as lumber or made into a wide range of products include outdoor furniture and offered at a premium price. Prices for these products range from $1 – $3 per linear foot for whole posts, and from $1.50 – $3.50/board foot for milled lumber, which is far above the prices for most conventional hardwood lumber.
Personally, at our farm, Black locust has found a nice in our pastures, where it quickly establishes itself and is able to be integrated with our sheep grazing paddocks in under 5 years. The sheep initially prune the lower limbs for feed, and we prune thicker branches to use for tree stakes, to plant more trees! We plant very close together (3 – 4 feet apart) so that over time, we can leave some trees as the overstory, while coppicing (cutting to the ground) and pollarding (cutting above browse height) the less straight ones to provide longer-term fodder reserves for the sheep. Eventually we can harvest some posts and poles, as well.
With all its functions and uses in the farm landscape, it’s a wonder more people aren’t planting these trees, and managing ones they already have. The key take away is; if you plant it, manage it. This wonderful tree has many benefits to harvest, but left along could become a problem plant on the farm.
Sources for Trees and Seeds:
Twisted Tree Farm, NY: http://twisted-tree.net/
Edible Acres, NY: http://edibleacres.org/
Sheffield’s Seeds, NY: https://sheffields.com
Cold Stream Farm, MI: https://www.coldstreamfarm.net
More information and slides from the workshop can be found at: http://silvopasture.ning.com/forum/topics/growing-black-locust-as-a-timber-cash-crop-in-the-northeast
This article is available for download at Wellspring Forest Farm & School’s website: https://www.wellspringforestfarm.com/
Is this considered an invasive species in Jefferson County. I have 8 acres in Ellisburg and would be interested in planting some.
Hi Gary – I’d recommend getting in touch with your local extension office (http://ccejefferson.org/). They will likely be able to provide you with a definitive answer. Good luck!
What are all the medical benefits from this tree? What can you do with the whole tree , I need to know we have a good many on my property.
Keep bees. They love the black locust flowers which make for a tasty honey
We moved into a home and the locust tree was cut down. How can we rid our yard from the root suckers?
Hi Shelia,
I would recommend reaching out to the staff at the NRCS Plant Materials Resource Center with your question: https://www.nrcs.usda.gov/wps/portal/nrcs/main/plantmaterials/pmc/northeast/nypmc/.
I am interested in ideas for establishing plantings in urban vacant lots. My city has many lots where houses have been torn down but where economics are not there to build. The lots are simply blocked off from street access and kept mowed. My thoughts were urban wooded lots maintained for the wood and potential bee keeping
Hi David,
I would recommend checking out our Guide to Urban Farming at this link: https://smallfarms.cornell.edu/2013/02/07/new-guide-to-urban-farming-in-new-york-state/
Good luck!
I love blacklocust trees but was always told that the leaves were toxic to animals. Did this only apply to horses or was it altogether incorrect?
Hi Heather,
I would recommend reaching out to the author of the article, Steve, with your question. He can be reached at sfg53@cornell.edu.
Hi! This information is great! I just learned today that I have one of these trees, in bad shape, in my yard. I recently burned a large pile of underbrush and wood from cleaning the place up. Little ones began popping up all over! I’m glad I found out wgat they were. The existing tree has been there for at least 2 decades. It is beyond help, but I hope to coach the little ones into better trees. Any tips?
Good article. I assume you don’t mean it when you say that to germinate, seeds should first be soaked in a pot of BOILING water for 12-24 hours. Sounds like bean soup!
I saw another video… The guy said he got water to boiling, turned it off, dropped the seeds in, and soaked for 24 hours… So… You’re right… You don’t actually boil the seeds the whole time…
I understand form an elderly gentleman from Italy(now deceased)that the saplings of locust, were shaped in a curved shape conducive to using for a ship or boats bow and keel and used thus because of the trees rapid growth and rot resistance properties.
How to find a lumber company willing to cut and mill this wood i have not been successful here in WI locust is considered a weed with no market available
Hi P h,
I’d recommend reaching out to your local extension team in WI with your inquiry: https://extension.wisc.edu/
I interplanted Black Locust trees with American chestnut and Black walnut trees over 25 years ago. The chestnuts are over 40 feet tall now. The Back walnuts have struggled.
Black locust trees have a tendency to split, requiring diligent pruning. Most of the Black locust trees are over 40 feet tall now.
Would coppicing these trees compromise the health of the chestnut and walnut trees?
When i bought the farmland over 40 years ago. The land was depleted from over farming the clay soil. Hence the reason for interplanting Black locusts.
You say there is a market for Black Locust wood?
I have been using a local tree pruning agency, but they are uninterested in preparing the wood for marketing.
My farm is in Oregon, and i don’t wan’t to pay for harvested wood i can’t sell.
Thoughts and advice
Very cool that you can plant American Chestnut in the Pacific NW. Enjoy!
You can contact Earthbilt (info@earthbilt.com) for help finding a mill interested in black locust.
Musser Forests in PA is a much cheaper source for Black Locust.
I live on the North Fork of Long Island (East Marion, NY) and birds drop black locust seeds onto my little garden. 2-feet tall little saplings come up every spring amid my wildflowers. I cut them off at the base, dry them and have excellent kindling. I love black locust!
Black Locust were planted – 4 ft spacing- for an agriforest project, 35 feet (legal) from an oil pipeline. Now I am concerned that over the years the trees might be a danger for the pipeline. I have considered cutting and poisoning the stump, and also coppicing above the 5 ft tree tube and managing the branches so they don’t go to seed (sounds like a lot of awareness and time).
I am concerned that coppicing like this might actually trigger the tree to send out runners and have new little trees popping up.
Any thoughts on this?
Curious about climate zones and rainfall requirements… What’s the minimum yearly rainfall, and the optimum yearly rainfall… I sounds like a good hard cold winter is no problem…
Thanks..
The flowers of the black locust tree are edible by humans. They smell and taste sweet and delicious. Honey made from them will be delicious also.
In my experience, while the heartwood is very rot resistant, the sap wood is not.
My dad put up a locust post in the center front opening of a garage he built. It was to be temporary but, 49 years later it is still there. It still has the bark on it and is still solid. The diameter is about 10 or 12 inches. I’m impressed.
Please don’t plant this tree. It is taking over natural areas in the MidWest.
I agree. This tree is very invasive. We get around 20 suckers a year and they aren’t easily removed. The thorns n the branches make handling the branches difficult and they trees themselves are weak and are easily broken during storms. There are better trees!!
We are finding out the same thing! Invasive, indeed! In our field we have one acre of 3-5 foot saplings grounding among poison ivy. How do we rid ourselves of these insidious trees and root structures? I’m not a farmer, just a retiree trying to manage a small but sizable piece of land?
The best way I’ve found to ensure that suckers don’t keep coming up from old root structures is to soak the cut stump of anything I cut with Tordon RTU immediately after cutting.
I just found out I have one large bush of it. I didn’t realize it was a tree, and a small one starting in another place in my back yard. I thought they were pretty until I looked it up and it says it’s poisonous to animals…I have a large dog that has been back there for a year and a half and has never gotten sick to my knowledge. But he’s an older dog and doesn’t chew on sticks anymore. But what if we got a new puppy? They chew on everything. Should I get rid of both trees because of the danger risk to them,? I’ve read that they are poisonous to sheep, cattle, horses, dogs, cats, if they eat the bark or other parts of the plant.
I have found the opposite to be true. My dogs chew sticks from them, goats, cows and horses (occasionally) eat the leaves and the blooms are covered in bees. I even tried tasting the flowers.
I’m no expert, just my observations.
Unfortunately, many plants and fungi get a false bad rap online because of paranoia from overzealous pet owners.
I was just watching a YouTube video about reforestation In Niger where Black Locust trees were used. When pruning the trees, the branches and leaves were fed to cattle. The comment was that although the leaves were toxic, cattle would self limit the amount to safely eat, but the leaves shouldn’t be fed to horses
This tree is great for farms but maybe not suited to urban lots. I have a few in my pasture and they are easily controlled by normal grazing and mowing, regular pasture maintenance.
Hi Liza
We want to plant them as tree lanes in our sheep pasture which we rotation ally graze. Am i correct in thinking the sheep will naturally keep the suckering in check without any other means of control. I have Steve book in which he hints at this but do you know of any evidence out there to support this?
Thanks
Paul Eaton
Hi
I have a self sown grove of locust. They will shortly be razed and will be the site of a drain field.
What can I do to keep whatever roots are still in the ground from sprouting? This is really important as it can impede the drain field.
Thanks from Parma MI USA
Hi Steve, thank you for praising a useful tree! I am a honeybee farmer. Locust trees are good for bees, as you mentioned.
I am worried about a trend at greenhouses to sell “seedless” locust trees. That means less helpful to bees. ~sigh~ People can forget that making nature “friendlier” to people can mean harmful to nature.
I think we can be creative enough to find solutions that benefit people AND nature.
As a Romanian, I have grown to love late Spring when the Locust trees are in full bloom through the streets of Bucharest. It makes a good “tree well”, or street tree, because the suckers have nowhere to go… And indeed, the honey from these flowers is incredibly fragrant… These days, we have a 10′ tall sapling that has volunteered in our yard at the foot of a tall (80′) Tulip Poplar, with just about 10′ distance between them. Both are close to the house. Do I let it grow, or will it weaken the larger tree, itself a “fast grower”? It is a bit too large to dig out and move.
I have straight locust growing everywhere. In Sherburne NY. Varying diameters. How can I prosper from this? Thanks
Black locust foliage helped my cattle through the drought of 2022 never had problems with sickness.in south oklahoma.I cut them down and they devoured them like candy.
I have 8 acres in VA with a semi wild wood line with mixed black locust. I have cut down the leaning and fallen trees over the last 10 years. I since learned the rot resistant feature of these trees. I have pulled out the various pieces, and hope to better manage the remaining black locust.
Do you have suggestions for the various pieces?
If I got confidence in the industry and trees I would consider expanding the trees to cover my field.
Suggestions?
Do you have to wash the fragrant blossoms before infusing them in honey?
What’s the best way to capture the scent?
I just learned that these trees are highly toxic and poisonous to animals and humans. We have a large one growing in our yard and after living with it for five years, my three dogs have all developed seizures along with liver & kidney issues and are now being treated for toxic exposure. Does anyone else have any experience with this?
This article opened my eyes to the incredible world of Black Locust! Who knew a tree could be so versatile? I’m already planning to build my dream home entirely out of Black Locust. Sustainable and stylish!
The Black Locust tree has several notable advantages, including its rapid growth rate, ability to fix nitrogen in the soil, and resistance to various pests and diseases. Additionally, its strong and durable wood makes it valuable for construction and woodworking, while its fragrant blossoms attract pollinators, contributing to ecosystem biodiversity.
Nice Post https://www.citizendailypost.com/
Nice post! informative! https://www.localobserverdaily.com/
Nice information! https://www.metrodailyreporter.com/
I have three black locust purple Royal trees that I saved from suckers from older trees they’re about 4 to 5 years old now and to this day they have not made any suckers at all. Also their flowers are white compared to the purple of their mother trees. They seem to be more healthy than the mother trees. But they are not grown as a single trunk tree they have two to three trunks on each tree.