Walnut, Black Juglans nigra
Prized for its nuts and attractive hardwood. Fragrant leaves. Likes deep, rich, well-drained soil; grows more slowly in drier soils. Grows to 50' to 75', 60' spread. (May self-pollinate, plant two trees to ensure pollination) (zones 4-9)Pricing Information
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Hardiness Zones 4 - 9The Black Walnut can be expected to grow in the zones shown in color in the arborday.org zone map. View Map
Type of treeNut Trees
Mature HeightThe Black Walnut grows to be 50' - 75' feet in height.
Mature SpreadThe Black Walnut has a spread of about 50' - 75' at full maturity.
SunThis walnut does well in full sun.
SoilThe Black Walnut grows in acidic, alkaline, loamy, moist, rich, sandy, well drained, wet, wide range, clay soils.
ShapeThis walnut has rounded shape.
The practical and the aethetic combine in black walnut to make this species one of the most treasured trees in American history. The valuable dark brown wood is strong with a handsome grain that polishes easily and gleams forever. The rich, flavored nuts are enjoyed fresh and retain their flavor and texture during cooking. Black walnuts have nearly twice the protein of English walnuts.
When grown in the open, the black walnut reaches 75' tall with a round, low branching, open crown that spreads nearly as wide as it is tall. In forests and plantations, the tree may reach 150' tall with a well formed trunk and lower limbs self pruned from « to 2/3 the distance from the ground. It develops a deep taproot and is difficult to transplant. The hard to crack shell encases a rich flavored nut. However, the crushed black walnut shells can stain fingers, clothing, and concrete. The trees bear in 12-15 years. (Partally self-fertile, plant multiple trees to ensure pollination) (zones 4-9) Alleopathy is the term given to the suppression of growth of one plant species by another due to the release of toxic substances. Black walnut tree roots contain juglone, a toxic substance released when the the roots of other juglone-sensitive species come in contact with walnut roots. You must keep a wide separation between the black walnut tree and susceptible plants. A partial list includes tomatoes, potatoes, peas, peppers, cabbage, alfalfa, serviceberry, chestnut, pine, arborvitae, apples, blueberry, blackberry, cherry, azalea, rhododendron, lilac, hydrangea, privet, members of the heath family. The black walnut's poison does not work on all species and some even seem to thrive on it.
The nuts are eaten by woodpeckers, foxes, and squirrels.
This native tree has been called our best friend in times of war and peace. Native Americans and early settlers used it for food, dyes, ink, medicine, fence posts, gun stocks, and furniture. Today black walnut wood is highly prized for paneling and furniture and the nuts for food.
Pinnately compound, alternate, 12"-24" leaves each consisting of 15-23, 2"-5" dark green leaflets. The leaflets are finely toothed.
The fruit consists of three layers: the round 1 1/2"-2" green fleshy husk borne singly or in clusters of 2-3, a black, hard, thick corrugated, 1-1 1/2" shell, a kernel with a rich, oily flavor. Walnut trees produce nuts in 8-10 years. They are harvested in early autumn.
Rate of growth refers to the vertical increase in growth unless specified differently. Rate, as is true for size, is influenced by numerous variables such as soil, drainage, water, fertility, light, exposure, ad infinitum. The designation slow means the plant grows 12” or less per year; medium refers to 13 to 24” of growth per year; and fast to 25” or greater.Manual of Woody Landscape Plants, by Michael Dirr.