Black Walnuts Facts

The black walnut tree, with the scientific name of Juglans nigra, was introduced to Europe in the mid-1600s, but it has not spread beyond America and Europe. It grows mostly in riparian zones, from southern Ontario, west to southeast South Dakota, south to Georgia, northern Florida and southwest to central Texas. Wild trees in the upper Ottawa Valley may be an isolated native population or may have derived from planted trees. Black walnuts are popular food sources in both America and Europe, and can be found in everything from candy, ice cream, fudge, and salads, as well as chicken, pork, and pasta dishes. Most parts of the tree including leaves, stems, and fruit husks have a very characteristic pungent or spicy odor. Fruiting may begin when the tree is 4–6 years old; however large crops take 20 years. A green rounded husk, 1½-2½ inches across, covers the round, hard, bony, dark brown or black nut. The kernel is oily, sweet, and edible.

Name Black walnut
Scientific Name Juglans nigra
Native Native to the eastern United States, as well as certain parts of Southern Canada.
Common/English Name Native to the eastern United States, as well as certain parts of Southern Canada.
Name in Other Languages Portuguese: Nogueira-preta
English: Black walnut
Swedish: Svart valnöt
German: Schwarze Walnuß
Spanish: Nogal americano
French: Noyer noir
Plant Growth Habit Large deciduous hardwood tree
Growing Climate Found growing along roadsides, fields, and forest edges in the eastern US. It will grow in closed forests, but is classified as shade intolerant; this means it requires full sun for optimal growth and nut production.
Soil Require a deep, fertile soil with a near-neutral or slightly acidic pH. It also tolerates relatively dry, poor soils, but with a significantly reduced growth rate.
Plant Size 70 feet tall by 70 feet wide
Root Deep & strong taproot  as long as 10 feet
Bark Typically grey-black and deeply furrowed into thin ridges which gives the bark a diamond shaped pattern
Trunk Tall trunk Under forest competition, it develops a tall and straight trunk. When grown in an open area it has a short trunk and broad crown.
Leaf Leaves alternate, compound, 1–2 feet long, with 11–23 leaflets. Leaflets 3–5 inches long, 1–2 inches wide, broadest below the middle, the end leaflet smaller than side ones or absent; margin toothed; upper surface yellow-green; lower surface paler, hairy. The leaves are overall dark green in color and are typically hairy on the underside.
Flowering Season April–May
Flower Monoecious. The male (staminate) flowers are in drooping catkins 8–10 cm (3 1⁄4–4 in) long. These are borne from axilary buds on the previous year’s growth. The female (pistillate) flowers are terminal, in clusters of two to five on the current year’s growth.
Fruit Shape & Size Small nut with a brownish-green, semi fleshy husk and a brown, corrugated nut. About two inches in diameter and are shaped like basketballs.
Fruit Color Green when immature, and yellow-black when ripe
Flavor/Aroma Robust, distinctive, natural flavor
Season September–October
Major Nutrition Total Fat (lipid) 74.16 g (211.89%)
Manganese, Mn 4.87 mg (211.74%)
Copper, Cu 1.7 mg (188.89%)
Phosphorus, P 641 mg (91.57%)
Tryptophan 0.398 g (90.45%)
Valine 1.589 g (75.24%)
Isoleucine 1.208 g (72.25%)
Histidine 0.84 g (68.18%)
Protein 30.08 g (60.16%)
Magnesium, Mg 251 mg (59.76%)
Leucine 2.105 g (56.95%)
Vitamin B6 (Pyridoxine) 0.729 mg (56.08%)
Threonine 0.901 g (51.19%)
Iron, Fe 3.9 mg (48.75%)
Vitamin B5 (Pantothenic acid) 2.075 mg (41.50%)
Selenium, Se 21.2 µg (38.55%)
Zinc, Zn 4.21 mg (38.27%)
Lysine 0.891 g (26.64%)
Total dietary Fiber 8.5 g (22.37%)
Vitamin E (alpha-tocopherol) 2.6 mg (17.33%)
Potassium, K 654 mg (13.91%)
Vitamin B2 (Riboflavin) 0.162 mg (12.46%)
Health Benefits
  • Cancer
  • Antifungal Action
  • Beneficial for Hair
  • Expels Parasites
  • Helps with weight loss
  • Immune System Health
  • Improved Reproduction in Men
  • Digestive Health
  • Respiratory Conditions
  • Heart Health
  • Skin Health
  • For Blood Sugar or Diabetes
  • Improves sleep
Calories in 1 cup (1 25gm) 774 K cal