Gleditsia is a genus of deciduous trees native to North America and Asia. Known by the common name of “locust trees,” this genus has around 12 known species, some of which are cultivated in gardens and orchards. Nurseries and garden supply stores sometimes carry Gleditsia seedlings and can also order them by request. Gardeners can also engage in exchanges with people currently growing these trees if they are interested in growing them.
Members of the Gleditsia genus have alternate, pinnately compound leaves and large, heavily branched crowns. The trees produce distinctive seedpods in the fall and are notoriously bedecked with protective thorns. The thorns grow both on the branches and the main trunk, and can be quite sharp. Older thorns usually turn brittle and break off with time.
In China, G. sinensis is used to produce compounds used in traditional Chinese medicine. Some practitioners wildcraft the materials they need, collecting them from trees growing in the wild, and others purchase commercially produced products grown in orchards and processed by manufacturers. Outside of China, these trees are primarily grown ornamentally and in some cases, defensively. A stand of locust trees can make a very effective deterrent to unwanted visitors in addition to creating a robust wind break to protect a home or garden from strong winds.
Several spineless cultivars have been developed for gardeners interested in landscaping with Gleditsia species without running the hazard of being poked by the spikes. These trees can be quite attractive, especially in the fall when the foliage starts to turn. However, even without spines, a locust tree can still be a nuisance, as the seed pods are large and very messy. This should be considered when deciding where to place a tree.
A properly treated Gleditsia can live for 120 years or more. When a seedling is initially planted, it should be established in deep, rich, well-drained, somewhat loamy soil. Periodic fertilization may be needed to keep the tree healthy and people should be aware that the root system can become quite deep and sprawling. It is important to deliver water around the tree, as well as to the base to ensure the roots get enough.
These trees are frost tolerant and very hardy. They can be grown in a wide range of climates. One thing to consider when establishing a Gleditsia is that some species can grow quite tall. They should not be planted in a location where they might overshadow a house or an area of the garden unless this is desired.