Black locust (Robinia pseudoacacia), are members of the legume family leguminosae. The tree is native to the U.S. and is also known as yellow locust. The tree can reach a height of 60 feet and have a width of 30 inches. Black locust trees bloom in May through June with whitish flowers that are fragrant. Seeds are produced September through April and can easily be propagated. Trees produce seeds at six years of age, but the best seed production occurs when the tree is 15 to 20 years of age.
Wait until the seedpods produced in September through April completely become ripe before picking. The seedpods will become brown, dry and will split open easily when they are ripe and ready for planting.
Plant the black locust seeds immediately or store them in an airtight container in the refrigerator until ready for planting. Black locust seeds will remain viable for several years if stored in an airtight container and cool environment.
Stratify the black locust seeds before planting for best results. Fill a small container with hot water and place the seeds into it. Allow the seeds to soak in the water for 24 hours.
Fill a planting container with drain holes with a lightweight potting mix that has organic material in it. Water the container.
Make a 1-inch indentation into the center of the soil with your finger. Place the black locust seed into the indentation and cover with soil.
Water the container again. Keep the soil moist until the germination process happens in anywhere from one week to two months. Continue watering the seedling to keep the soil moist but not flooded.
Place the container in an area that receives full sunlight to partial sunlight throughout the day. Though shade tolerant once established in the ground, the seed will need sunlight to germinate properly.
Transplant the black locust into the ground once it has developed an established root system in its container in approximately four months.