Black walnut is a native of eastern and central North America. Useful as a shade tree, it is a source of nuts and a prized hardwood for carpentry and building. Black walnut is adaptable to many areas; the eastern native's largest known specimen is in Oregon. Plant a black walnut in your large yard. Enjoy the shade and nuts, and the native grace of this large tree.
Black walnut occurs naturally down into the south, but not in areas that are primarily hot or dry. There are occasional black walnut trees in the Canadian upper Ottawa valley, but it has not been determined if these are native or if they are the result of human cultivation. The black walnut has also been grown in Europe since the 1600s.
The black walnut is a deciduous tree reaching 30 to 40 feet. It has a longer, straighter trunk in the forest; it will have a shorter trunk when planted in a yard. Bark is dark gray and furrowed. The nuts mature in the fall. The nuts are in a very hard case. The tree bears more abundantly in alternate years.
Black walnut wood is heavy and strong, but it is easily split and worked. The wood is used to make furniture, flooring, coffins, gunstocks and paddles among many products. It is also a highly prized source for veneer. Even the odd pieces of black walnut can be used to create highly prized decorative pieces and artwork.
The nuts of black walnut are highly prized in cooking and baking. They are also pressed to extract an oil used as a flavoring agent and a natural health remedy. The shells have historically been used as a dye for cloth and skin; today they are valued more for their hardness and are used as an abrasive and in cosmetics. The shells are also used in oil drilling and water filtration.
Pests and Diseases
Black walnut trees have few disease problems, however, extreme cold can do severe damage. Damaged trees can be infected by fusarium canker. Walnut foliage, twigs and nuts can be damaged by fall webworm, walnut caterpillar, husk fly, walnut shoot moth, walnut lace bug, plant hoppers, black walnut curculio, pecan leaf casebearer and aphids. Livestock can compact soil, injure bark and branches and eat twigs and leaves. Wounded trees become susceptible to diseases.
Black walnut is one of the Midwest's most valuable tree species based on price per board foot. It has long been in high demand throughout the world for wood products because of its beautiful color, strength, durability, dimensional stability after drying, and excellent machining qualities. Top-quality logs are sliced into veneer. Black walnut has been and continues to be a premier hardwood marketed throughout the world.