The most common types of locust tree are the black locust, or Robinia pseudoacacia, and the honey locust, or Gleditsia triacanthos. Both are native North American plants used for landscaping. Locust trees normally have sharp thorns, but some cultivars of the honey locust are thornless.
Locusts are hardy in U.S. Department of Agriculture plant hardiness zones 4 through 9. They are easy to grow in full sun but do not tolerate shade well. They prefer deep, moist, well-drained soil. They tolerate drought, compacted soil, salt and urban pollution well, but need to be protected from salt spray during the first year after planting.
Black locusts grow up to 80 feet in height but are more commonly 30 to 50 feet tall with a spread of 30 feet at maturity. These trees have an irregularly shaped canopy and are good choices for shading plants that do best in partial sun. Their clusters of flowers are attractive to bees. Black locusts require regular pruning to remove suckers.
Honey locusts reach mature heights of 30 to 40 feet with somewhat lesser spreads. They have attractive fall foliage, and the 'Suncole' cultivar boasts yellow foliage when it begins leafing out in the spring. Honey locusts produce sweet fruits that are attractive to wildlife but are messy. Some cultivars produce very few seed pods, making them good choices for lawns.