Black Locust, America’s Super Tree

Although virtually forgotten, the benefits of black locust wood are astounding; 100 year life in the ground without preservatives, bee-loving flowers for sweet honey production, the highest tensile beam strength of any American tree including Ironwood, ability to immediately stabilize erosion-prone hillsides because of their rebar-like interlacing root system, improve soil by fixing plant loving nitrogen to its roots and one of the highest BTU (British Thermal Unit).

Black Locust wood contains natural organic compounds that resist rot for 100 years or more, which makes these trees an extremely valuable and environmentally friendly tree. It is the perfect wood for fence and deck posts. In fact, old telegraph lines still standing in the west, have their original locust poles sticking out of the ground 150 years later.

Black locust trees (Robinia pseudoacacia) are known for their rot-resistant properties. This is because the heartwood of the black locust tree contains a natural preservative called robinin, which makes it highly resistant to decay and insect damage. Here are some of the key properties of black locust that make it such a popular choice for outdoor use:

  • Durability: Black locust wood is highly durable and can last for decades without rotting or deteriorating. This makes it a popular choice for outdoor furniture, decking, and other outdoor structures.
  • Resistance to decay: The robinin in the heartwood of black locust trees makes the wood highly resistant to decay and insect damage. This makes it a good choice for applications where the wood will be exposed to moisture or soil, such as fence posts and retaining walls.
  • Strength: Black locust wood is also known for its strength and hardness, making it a good choice for applications that require a sturdy and long-lasting material.
  • Low maintenance: Because of its rot-resistant properties, black locust wood requires little maintenance and can be left untreated in many outdoor applications.

Black Locust, Black Locust Tree, Black Locust Wood Video

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These trees helped build early colonial towns and hardened navy sailing ships (along with ironwood) that decided the War of 1812, yet today few Americans have heard of it. The extreme resistance to rotting is perhaps the best black locust attribute, and it was on poles of black locust that the first buildings were erected in early colonial America. Some of these poles are still in use today as sound as the day they were driven into the ground. (Wesley Greene - garden historian for the Colonial Williamsburg Foundation)

Here are some examples of historical structures that have used black locust wood and have been in the ground for over 100 years:

  • The C&O Canal: The Chesapeake and Ohio Canal, which runs from Georgetown in Washington, D.C., to Cumberland, Maryland, was constructed in the mid-19th century using black locust wood for its locks, lock gates, and aqueducts. Many of these structures are still in use today and have been in the ground for over 150 years.
  • The Brooklyn Bridge: The Brooklyn Bridge, completed in 1883, was constructed using black locust wood for its suspension cables. While the original cables have since been replaced, some of the original black locust wood remains in the bridge's construction.
  • The Mount Vernon Estate: The Mount Vernon Estate, home of George Washington, features a historic fence made from black locust wood that is over 200 years old. The fence still stands today and is a testament to the durability of black locust wood.
  • The Biltmore Estate: The Biltmore Estate in Asheville, North Carolina, features a pergola constructed from black locust wood that is over 100 years old. The pergola still stands today and is an example of the long-lasting properties of black locust wood.
  • Harvard Forest: The Harvard Forest, a research forest in Massachusetts, has a number of experimental plots that were established in the early 20th century using black locust fence posts. Many of these fence posts are still in place and in good condition over 100 years later.
  • Ford Island Bridge: The Ford Island Bridge, which connects the main island of Oahu, Hawaii, to Ford Island, was constructed in the 1910s and used black locust wood for its pilings. The pilings are still in use today, over 100 years later.
100 year old black locust telegraph pole

The Problem With Pressure Treated Lumber

Its importance as a non-toxic chemical free wood cannot be understated given the present state of the environment and water quality across the country. The toxins leached from the pressure treated lumber in use over the past 50 years have done immeasurable damage to the environment.

Pressure treated lumber has been used extensively over the past 50 years for outdoor construction, such as for decks, fences, and playground equipment. These materials are typically treated with chemicals to protect against decay and insect damage, but there are concerns that these chemicals can leach into the environment and cause harm.

The most common chemicals used in pressure treated lumber are chromated copper arsenate (CCA), which contains arsenic, and alkaline copper quat (ACQ) or copper azole, which contain copper. Both of these chemicals have been found to leach into the soil and groundwater, potentially causing harm to plants, animals, and humans.

Studies have found that arsenic and copper can accumulate in the soil over time, potentially reaching levels that are harmful to plant growth and ecosystem health. These chemicals can also leach into surface and groundwater, potentially contaminating drinking water sources and harming aquatic life.

There is also concern about the potential health effects of exposure to arsenic and copper. Arsenic is a known carcinogen and has been linked to a range of health problems, including skin lesions, cardiovascular disease, and cancer. Copper can also be toxic in high concentrations, causing gastrointestinal and liver problems in humans and animals.

While the use of CCA-treated lumber has been largely phased out in recent years due to concerns about its environmental and health impacts, there is still a significant amount of pressure treated lumber in use that may be leaching chemicals into the environment. To reduce the environmental impact of pressure treated lumber, it is recommended to use alternative materials, such as naturally rot-resistant woods like black locust.

North American Growing Zones For Black Locust Trees

Black Locust native growing areas are concentrated in the Eastern United States, with the highest concentration in the state of Ohio. Although native to Eastern North America, this tree will grow in micro-climate areas of the Western States and Canada, principally the central interior of British Columbia, Canada and Washington State.

1north american black locust growing zones

Black Locust Tree Plantations

Because this tree has virtually been forgotten, there are no commercial black locust plantations in the United States, which presents a unique opportunity to grow a profitable tree and corner the market. Wide plank dimensional lumber is unheard of and yet it is more durable and attractive than oak for floors. Long length post and beams are extremely hard to find, certainly anything over 6 inches square.

In advance of starting a locust plantation, a grower has little choice but to grow seedlings from seed due to a general unavailability of nursery stock. This, however, can be an advantage for two reasons; the first is that black locust seedlings can be offered for sale and second, black locust seedlings can be manipulated using our proprietary methods to grow seedlings into tall 10-foot saplings. Transplanting tall locust saplings will shorten time to harvest in a plantation and give timber investors a faster return on their capital.

10 foot tall black locust tree seedlings

Typical tree plantations cultivate trees in parallel rows over large acreages. These mono-cropped plantations are susceptible to the elements, particularly wind gusts that can penetrate the spaces between tree rows. Bud winterkill is a common occurrence during the dormancy season.

We grow trees in large geometric spirals, which accelerate growth and protect the trees. In an initial planting, black locust saplings are transplanted 10 feet apart along the length of the spiral, which could be over 10,000 feet long in a 5-acre plantation depending on spacing between rows. Transplanting 10-foot-tall saplings in effect creates an instant forest the second year after transplant. In year 15, every second tree is culled for pole wood and pellets leaving the remainder of the trees to mature for timber wood in year 30.

After harvest, the stump of each tree regrows a new one the first year after harvest. Newly sprouted trees grow much faster than the original transplanted saplings (sometimes 10 feet in one year) because they are feeding off a mature root system.

Honey Production

Black locust blooms just 10 days a year each season producing the finest blossoms for making locust sweet honey. This short bloom makes locust sweet honey rare and expensive. Certainly, a consideration to develop a secondary income.

Black locust trees (Robinia pseudoacacia) are indeed known to produce high-quality honey, which is prized for its light color, delicate flavor, and slow crystallization. Here are some of the reasons why black locust tree flowers are preferred for honey production:

  • High nectar production: Black locust trees produce large quantities of nectar, which is the main ingredient in honey. This means that bees can collect a lot of nectar from a single tree, which makes it an efficient choice for honey production.
  • High sugar content: The nectar of black locust tree flowers has a high sugar content, which means that bees can produce honey with a high sugar content as well. This makes the honey sweeter and more flavorful than honey produced from flowers with lower sugar content.
  • Unique flavor: The nectar of black locust tree flowers has a unique flavor that is described as sweet and floral, with hints of vanilla and almond. This gives black locust honey a distinct flavor that is highly prized by honey enthusiasts.
  • Slow crystallization: Black locust honey has a slow crystallization rate, which means that it stays liquid and spreadable for longer than many other types of honey. This makes it easier to use in cooking and baking, and also makes it more appealing to consumers.

Overall, the high nectar production, high sugar content, unique flavor, and slow crystallization rate of black locust tree flowers make them an excellent choice for honey production, and black locust honey is considered by many to be a premium product with superb natural flavor.

Black Locust Wood

The following comments were collected from a national wood products discussion forum.

Comment from contributor A:

I am a wood-flooring contractor and have installed a couple black locust floors. Not only is it tough (second only to osage orange as the toughest native wood) and resistant to moisture (much better than white oak) and rot (way better than cedar), but it is also gorgeous! If you haven't seen it, picture the grain of oak and color it with gold and add a glow that shifts in the light. The wood is tougher than hickory, which is tougher than hard maple, which is tougher than oak. I have gotten it for only slightly more than the price of oak. I only wish there was a supply of this lumber in my area. I'd make everything out of it. It has a very low rate of expansion and contraction, making it very stable for furniture and woodwork (interior or exterior). Hard to work? Well, it's not balsa. Whaddaya expect when it's practically the most durable and stable wood available? Use sharper tools.

Comment from contributor B:

Posts made of this wood are good for grapevine supports in vineyards. It lasts longer than pressure treated wood, and it does not leak harmful chemicals into the soil as pressure treated wood does, such as arsenic, which can be absorbed by the plant and therefore into the fruit. Vineyard posts are usually 8 feet long and about 4.5 inches in diameter. In a vineyard, 1.5 to 2 feet of the post is put into the ground, depending on the soil, and two to three wires are run between the posts on which the grapevine is tied. Locust can also be used for fence posts. There is no need to use a waterseal. Great for the environment - great for the grapes.

Comment from contributor C:

As a bandmill sawyer, last year I started sawing the wood, and what a surprise, it saws just as easy as cherry, and the grain and color is out of this world. I sawed a couple hundred board feet the other day to use as a floor for a kiln, due to the moisture resistance. Locust wood is the most under-rated lumber out there.

Comment from contributor D:

I have about 20 cords of locust logs from a land-clearing job we did last summer. It's a wonderful species for firewood – it burns hot and long if properly seasoned. It's also very rot resistant and commonly used for fence posts and exterior construction on farms. It is also a fast growing pioneer tree here in the northeast - meaning it's one of the first species to appear in fields left fallow. The tree will seed itself in these old pastures and grow in dense stands that are very straight and tall (sometimes over 100 feet). At least it used to before the beetle borers showed up.

Comment from contributor E:

I live on Long Island near the abandoned Kings Park Psychiatric Hospital. The hospital itself was established pre-1890, and the grounds (400+ acres) were apparently planted with many of these trees, many of them now over 75-80 feet in height. Some of the older ones were cut down by N.Y. State in its infinite wisdom, and I was able to take out about a cord and a half as firewood. Let me tell you what, once properly split and dried, that wood was among the best I have ever burned in my heatilator-equipped fireplace. It burns slowly, and very hot. The key mechanism here is to make sure it is properly stacked and dried; this will keep spitting during burning to a low level. While splitting the wood one can't help but notice a beautiful gold-green sheen to the heavy, straight veined splits. Locust wood is as hard as any I've ever worked with, and it is of the highest quality!

Comment from contributor F:

I was fascinated by your blog on this tree, which I’m in love with. I’m a 75-year-old (ouch) amateur cabinet maker and have just completed a desk using this wood, and before that a six foot long sideboard. It is absolutely fabulous wood to work with and to look at when finished. I gather it is also called false acacia. I live in (West) Vancouver BC, and in a huge windstorm in 2006, this tree was blown down. I got most of the trunk and had it milled. Apparently, acacia, as many call it, was planted along the Fraser River as fuel for the paddle wheelers in the 19th Century and is occasionally milled around here. I agree with others that Black Locust should really be promoted for all its potential uses.

Comment from contributor G:

We have found at least 5 advantages for the lazy grower like myself. First, is fast growth, outgrowing in dry clay almost all other species. Second, the wood is not easily damaged by extreme foraging for two reasons, the short thorns on many trees discourage some foraging, but you also have a wonderful hidden asset, even if the tree is completely stripped of bark by winter foraging deer, the runners and underground storage of food insures it will grow back even stronger the following season, not just stronger but often taller and with friends. Third, that root regeneration insures reforestation even after harvest, mechanical damage, or fire. Fourth, the root provides a degree of allelopathy, thereby suppressing other competing weed trees like Eleagnus and red cedar. And so far, we have had less attack by insects and fungus compared to oak, walnut, persimmon, and pine. Plus, it smells good in the Spring.

More Black Trees

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The best time to plant black locust trees was 20 years ago.
The second best time is now!