The black walnut tree (Juglans nigra) is native to the United States and is one of the hardiest, most valued American trees. It can grow to more than 100 feet tall and live to be more than 200 years old. The nuts are high in fat and rich in flavor, and are consequently prized by animals and people. Commercial lumber companies farm black walnut trees, which are used for furniture, cabinets, doors and paneling.
Vertical Growth Rate
According to the Arbor Day Foundation, black walnut trees grow at a medium rate--13 to 24 inches each year under ideal conditions.
The trees will grow in USDA hardiness zones 4 to 9. This includes most of the continental United States except for the extreme northern portions of Montana, North Dakota and Minnesota, the extreme tips of Florida and Texas, and the desert region on the border between California and Arizona.
Unlike many trees, the black walnut will grow in just about any soil--sandy, rocky, clay, loam, wet, dry, rich or poor--so the quality of the soil doesn’t have much affect on its growth.
Sun and Space Requirements
Black walnut trees prefer to grow in full sun. In a sunny, open area, a black walnut tree will eventually grow to 75 feet tall and can spread into a rounded shape that can cover an equivalent area.
In tighter quarters, such as tree plantations where rows of seedlings are set out side by side, black walnut trees will grow to heights of 150 feet or more. The lower limbs will self-prune so that about two-thirds of the trunk will be bare before the branches spread out at the top.
Growing Black Walnuts
The trees don’t start bearing nuts until they’re 10 to 15 years old. While some trees do sprout naturally in the wild from fallen nuts and from the stumps of fallen trees, the University of Minnesota Extension Service advises people to either plant the nuts to generate a new tree or to buy black walnut seedlings.
The black walnut tree has a single, very large taproot, which makes it hard to transplant successfully once it’s established itself. Attempting to transplant a black walnut will almost certainly slow its growth, if not kill it.