Black walnut trees are native to North America. They are a prized tree, not only for their nuts, but also for their strong wood and long life span. They grow naturally in the Eastern United States but can be grown throughout the Midwest and up through Canada. They are hardy to USDA zones four through nine and many varieties are available for planting in a home garden. However, if you want your black walnut tree to bear nuts, plant two or more trees of different varieties so they may cross pollinate.
Choose a spot to plant your black walnut trees. Black walnuts grow best in full sun with little to no surrounding plants for competition. The PH of the soil can be between five and seven. Black walnuts grow best in thick, well-drained soil.
Dig a hole for your tree about three or four feet deep and four feet in diameter. Place the tree in the hole, cover it with soil and add mulch. Space each tree about fifty to seventy five feet from each other to allow ample growing room.
Water your black walnut tree once a week in the spring and summer for ten minutes each watering. Water only once every month in the fall and winter for ten minutes each watering.
Add one cup of 10-10-10 fertilizer to the base of the black walnut tree early each spring starting the year after the tree is planted. Water after applying the fertilizer.
Prune your black walnut tree at three years of age and every year after that in the spring. Prune all but the strongest leader. Cut back any broken or dead branches and any branches that are overreaching or growing vertically. Allow a space of about seven inches between each branch. Cut off any low-lying branches. There should be enough room for people to walk under the tree.
Harvest your black walnuts after they fall off of the tree, usually in late summer and early fall. A black walnut tree takes ten years to produce nuts.