Boone County Arboretum
9190 Camp Ernst Road
Union, Kentucky 41091
Phone: (859) 384-4999
Fax: (859) 384-6888

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Cultural Details for Juglans nigra

Common Name:
Black Walnut

Growth Rate:
Fast, 2-3' per year on favorable soils when young

Average Mature Height:

Average Mature Width:

Flower Details:
Yellow, late May - early June, monoecious: male flowers clustered in short, pencil-like drooping catkins

Fruit Details:
Corrugated nut in a green, smooth, 2" diameter husk which turns black and rots on ground.

Fall Color:
Golden yellow, drop early

Bark Details:
Dark brown to grayish-black, divided by deep, narrow furrows into thin ridges, forming a roughly diamond-shaped pattern

Disease / Insect Problems or Resistance:
Roots exude a substance toxic to many other plants, few insect or disease problems on healthy trees.

Native Habitat:
Massachusetts to Florida, and west to Minnesota and Texas

Other Features:
Wood is highly prized for carpentry uses. Branches have a chambered pit. Roots produce juglone which is harmful to many other plants growing in its root zone.

Culture and Care:
Prefers deep, rich, moist soil but can tolerate drier, clay soils zone 4-9

This plant was blooming:

Plantings of this cultivar at Boone County Arboretum:
980, 1233, 1234, 1235, 1236, 1237, 1238, 2214, 2285, 2532, 2538, 8614, 8615, 8616, 8630

    The information on this page may have come from one or more of the following sources:
  • Dirr, Michael. Manual of Woody Landscape Plants. Stipes Publishing. 1998.
  • Hightshoe, Gary L. Native Trees, Shrubs, and Vines for Urban and Rural America. John Wiley & Sons. 1988.
  • North Carolina Extension Plant Fact Sheets.
  • University of Connecticut Plant Database.