Eastern Black Walnut (Juglans nigra) Care Guide

What Is Eastern Black Walnut and Where Does It Come From?

Juglans nigra, the eastern black walnut, is a large deciduous tree native to the eastern and central United States, prized for its rich, dark, highly figured wood, its edible nuts, and its imposing shade canopy. Mature specimens typically reach 20-30 m tall with a broad, rounded crown and can live well over a century. The pinnately compound leaves, made up of 15-23 lance-shaped leaflets, turn a soft yellow in autumn before dropping early, and the deeply furrowed, dark gray-brown bark gives older trees a rugged, sculptural silhouette. In spring, inconspicuous green catkins appear alongside the emerging leaves, followed by round, thick-husked nuts that ripen in fall and stain hands and pavement a deep brown. One of the tree's most distinctive traits is allelopathy: its roots, leaf litter and nut husks release juglone, a chemical that suppresses or kills many nearby plants — including tomatoes, azaleas and blueberries — within its dripline, so it is best planted well away from vegetable gardens and ornamental beds. Juglone and other compounds in the shavings and hulls can also be irritating to dogs and, notably, toxic to horses if used as bedding. Despite these quirks, black walnut is a valuable wildlife tree, feeding squirrels and other mammals, and its lumber is among the most sought-after hardwoods in North America.