Black walnut seed is heavy. Many black walnut seedlings germinate from the nuts cached by squirrels in the fall. It grows slowly on wet bottomlands, dry ridges, and slopes. Good agricultural soils are generally favorable sites for black walnut. Principal associates are identified in the Distribution and Occurrence frame.
Black walnut is classified as shade intolerant.
Black walnut is found in many of the climax associations but because of its intolerance is not classified as a climax tree in the strict sense.