A great tree for producing quick coverage, black locust is prized for its rapid growth. Plant a trio of these easy-to-grow trees where you would like to block a view, perhaps of a neighbor's backyard or a nearby development. At maturity black locust reaches 30 to 40 feet tall and about 20 feet wide, making it a lush and leafy living screen. In many areas, black locust is plagued by internal decay, giving it a weak structure and making it a liability to the property owner. Be sure to consider the liability of black locust before planting.
Black Locust Care Must-Knows
Black locust is known for its ability to grow in almost any type of soil. Dry sandy soil—no problem. Compacted soil in an urban area—no problem. Boggy soil that dries occasionally—it grows here too. The only soil that limits black locust growth is soil that is always wet. Streamside and ravine planting spots are often too wet for black locust, but a rain garden, which dries from time to time, is a great planting area.
Easy to transplant and establish, black locust requires little extra care beyond regular watering the first year after planting. Internal decay, borers, and black locust leaf miner regularly threaten black locust trees in the landscape. Borers and leaf miners rarely kill a tree but they do give it a brown appearance in late summer after they have ravaged the foliage or wood. The tree often recovers fully the following growing season.
Internal decay can kill a tree. The overall tree structure becomes weak and the tree will break apart in wind storms. It is critical to monitor the health of black locust trees in urban and suburban landscapes. A weak tree can damage property or endanger people.
More than a quick-growing tree, black locust is also beloved for its ropelike clusters of pink and white flowers in mid-spring. The flowers are frequent stopping points for bees. Black locust honey is prized for its rich flavor. The flower clusters are followed by flat, papery fruit pods. The pods are usually 2 to 4 inches long and don't make a mess in the landscape.
More Varieties of Black Locust
Robinia pseudoacacia is the wild form. It's fast growing, offers fragrant white flowers, and reaches 80 feet tall and 50 feet wide at maturity. Zones 4-9
Golden black locust
Robinia pseudoacacia 'Frisia' has white flowers and bright golden-yellow foliage in spring and summer that turns orange in fall. It grows 50 feet tall and 25 feet wide. Zones 4-9