Black walnut trees typically are grown commercially for lumber or for their nuts, but that doesn't mean you can't have one in your backyard. While you can plant black walnut seeds, you will have greater success transplanting a seedling. Black walnut trees require at least 25 inches of rain annually and 140 days without frost.
Select a seedling. You can purchase one from a nursery, or you can look for one near an established black walnut tree and dig it up. Choose a seedling that is at least 1 year old with a 1/4-inch to 1-inch stem. Measure the diameter 1 inch above the base of the tree.
Select a planting site in full sun to partial shade. The soil should be moist and well-drained. Black walnut tree roots grow deep, so the soil should be free from bedrock for at least 30 inches. Avoid areas that flood during the growing season. Choose a location that is not too windy or susceptible to ice. In addition, give your tree space if you want it to produce lots of nuts--200 to 300 feet around the tree is ideal.
Dig a hole as deep as the root ball but two times as wide. Set the seedling in the hole, backfill with soil, and tamp it down to remove air pockets. Water the tree well. Supplement with more water if it does not rain the required 25 inches per year, the majority of which should be during the growing season.