Robinia pseudoacacia, commonly called black locust, is medium sized deciduous tree that typically grows to 30-50’ (less frequently to 80’) tall. It is native to the Allegheny Mountains in the west-central Appalachian Mountains. It will grow as a broadly columnar single trunk tree with a narrow oblong crown. It is noted for its attractive compound leaves and pendant racemes of pea-like flowers. Branches are usually armed with short paired spines (to 1.25” long). Pinnate dark blue-green leaves, with each leaf having up to 23 lance-shaped to ovate leaflets. Leaves turn uneventful yellow in fall. Fragrant wisteria-like white flowers in pendant racemes (to 8” long) bloom in late spring. Bees are attracted to the flowers. Flowers are followed by smooth, flat, purple-brown seed pods (to 4-5” long). This species is also commonly called common locust, yellow locust, white locust, green locust, pea flower locust and false acacia. Grow in average, dry to medium, well-drained soils in full sun. Tolerates some light shade, but avoid shady locations. Tolerates a wide range of soils including sandy or nearly barren ones. Best performance is in moist, organically rich loams. Good drought tolerance. Fixes nitrogen. Black locust is generally considered to be a very easy-to-grow tree. It thrives in many difficult growing conditions.

Growing Instructions

The seeds have a hard seed coat that has to be treated, or scarified, in order for water to enter the seeds so that they can sprout.

Scarify the seeds by nicking or sanding the seed coat. The seeds can be sanded with sandpaper, a nail file or an emery board.
Soak the seed in water for 12-24 hours.
The seeds like moist, well-drained soil. Prepare a mixture of half potting soil and half sand, perlite or vermiculite. Put the soil in a pot. Water the mixture so that it is moist but not wet.
Put the seeds on the soil.
Cover the seeds with a layer of soil.
Water the seeds.
Place the pots in an area in full sun or part shade. The seeds should germinate in a few weeks.
When the seedlings are a few inches tall, they can be transplanted.