Black Walnut

General
Scientific Name: Juglans nigra
Family: Juglandaceae (Walnut)
Hardiness: Zone 4
Leaves: Deciduous
Plant Type: Tree
Growth
Rate: Medium
Mature Height: >45’
Longevity: Long
Power Line: No
Ornamental
Flowers: Inconspicuous
Fruit: Green to black nuts
Fall Color: Yellow

A large oval to rounded, somewhat open-crowned tree. Very valuable timber tree. The tree is borderline hardy in North Dakota and some seedling sources will be subject to winter dieback. Choose hardy North Dakota seed sources. The largest tree in North Dakota is 65 feet tall with a canopy spread of 50 feet.

Light: Full sun, tolerates partial shade.
Water: Prefers moist soils, does not withstand extended ponding or drought.
Soil: Sensitive to soil conditions. Does best on deep, fertile soils.

Black walnut will produce seeds after 4-6 years of age, however the husks can stain sidewalks and clothing. Black walnut roots produce chemicals called juglones which are very toxic to certain other plants such as azaleas, rhododendrons, blueberries, peonies and solanaceous crops (tomatoes, peppers, potatoes). Most of the toxicity is limited to within the drip line of the tree, but the area of toxicity typically increases outward as the tree matures.