The Advantages and Disadvantages of Growing the Invasive Black Locust Tree in Your Yard

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The Advantages and Disadvantages of Growing the Invasive Black Locust Tree in Your Yard

The Black Locust tree is a sight to behold, but is it worth the potential problems it may cause? It’s interesting to note that while this tree is native to North America, it’s considered invasive outside of its natural range. This is mainly because of its aggressive growth pattern and tendency to overtake natural areas. However, some people hail it for its benefits as a nitrogen fixer and erosion-preventing timber in the natural landscape. One thing is certain: if you choose to plant this tree, whether it’s within its native range or not, you must manage it.

The black locust is not a tree that you can leave to its own devices, as it will quickly dominate the surrounding area. Additionally, its branches are covered in thorns, so it’s not ideal for forming dense thickets unless you plan to use it as a living fence. This characteristic can indeed come in handy in this case. The most common mistake people make when planting garden trees is not considering their growth pattern and the surrounding area. With the black locust, it’s crucial to conduct thorough research on the tree and determine where or if you want to incorporate it into your yard.

What is the Black Locust tree?

black locust tree covered in flowers

Orest lyzhechka/Shutterstock

A member of the Fabaceae family, the Black Locust is a leguminous, nitrogen-fixing tree originally native to the Appalachian mountains. It can reach heights of 100ft with reddish brown to black bark. The branches are covered in thorns occurring at each node, and in the spring, the tree emerges with a striking display of white, fragrant flowers. The flowers are edible and taste like a sweet candied pea. However, it’s important to note that the rest of the tree is toxic for humans, including the leaves. Additionally, the flowers are an important nectar and pollen source for native bees, honeybees, hummingbirds, and other pollinators.

The Black Locust timber is one of the strongest native to North America. The wood is hardy, rot-resistant, and incredibly durable. It was brought from the Appalachian mountain range to the West Coast of the US during the Gold Rush by pioneers who grew it for timber. Since then, it has completely escaped its native range and naturalized throughout the US and even in parts of Europe and Asia. However, it is important to distinguish between invasive plants and aggressive growers. Aggressive growers often include native plants and refer to the plant’s intense growth habit and ability to take over a landscape without intervention. Invasive plants both take over an area and do not support the native ecosystem in any capacity. While aggressive native plants may choke out other native vegetation, they also support the local ecosystem in other ways.

Pros and cons of growing the Black Locust tree

thorns growing on black locust tree

This_is_JiHun_Lee/Shutterstock

As we already established, the Black Locust tree is widely considered invasive. It’s a very hardy and competitive plant, and it spreads by root suckers and rhizomes, as well as by seed, so it can quickly take over an area if not managed properly. In addition to its aggressive growing habit, it proliferates quickly, allowing it to form dense clusters that out-compete native vegetation. It poses threats to different kinds of native habitats, from oaklands to savannahs, due to its preference for dry, well-draining soil and its aggressive suckering growth habit that chokes out other native vegetation.

However, in the farm landscape, there are a plethora of benefits that the Black Locust has to offer. One of the benefits of Black Locusts is that it’s fast-growing, fixes nitrogen into the soil, thereby building healthy soil, and creates an excellent windbreak, living fence, or shelter for livestock in a matter of months. The rot-resistant wood is a great option for fence posts, outdoor furniture, decks, and other weatherproof wood projects. Additionally, due to its ability to build soil and fix nitrogen, it is used in reforestation projects and for stopping erosion. While the Black Locust can be invasive in certain settings, it is a highly beneficial tree in well-managed landscapes. It is not recommended in residential areas as it has thorns and can aggressively take over gardens and surrounding areas. However, it’s an excellent ally if you can commit to managing it.

Dr Heidi Parkes

By Dr Heidi Parkes

Senior Information Extension Officer QLD Dept of Agriculture & Fisheries.