Black Walnut, Eastern Black Walnut

Scientific Name: Juglans nigra L.
Family: Juglandaceae

Recommended Temperature Zone:
Sunset®: 1-9,14-21
USDA: 4-10

Sun Exposure: Full sun

Origin: Eastern North America, southeastern New Brunswick to northern Mississippi

Growth Habits: Deciduous tree, 50 to 75 feet tall (15-23 m) or more; alternate, odd-pinnately compound leaves, with the terminal leaflet missing or misshaped, 12 to 24 inches long (30-60 cm), with 10 to 23 serrated leaflets, 3 to 5 inches long (7.5-12.5 cm), odoriferous when bruised

Flowers: Light yellow or greenish flowers

Watering Needs: Moist, well drained soils, relatively drought resistant

Propagation: Named varieties are grafted on same species seedlings

Propagation: Seed or occasionally cutting, layering, grafting/budding

• by softwood, hardwood stem tip cuttings, in winter. Apply IBA TALC 8000 PPM. Use intermittent mist. Root in 6-8 weeks. Wound cuttings..
• by air, trench layers, in late winter. remove a ring of bark.
• by whip, 'T' grafts. Use a J. Hindsii or Paradox Hybrids as graftstock. The best time for grafting/budding for whip is Spring and for 'T' is Autumn. Seedlings are cut off 10-14 days before grafting for the sap to dry. When the grafter begins seedlings are cut 1-2 inches to remove the dry surface.
• by seeds, in spring. Germinates at 70-85 degrees F. The seeds can be harvested in autumn. The seeds need stratify 40F 4-5mo.. The usual germination temperature is 70-85 degrees F.

Juglans nigra bark, Robert H. Mohlenbrock. USDA NRCS. 1995. Northeast wetland flora: Field office guide to plant species.

Blooming Habits:
The male flowers are long catkins, 2.4 to 5.6 inches long (6-14 cm). The female flowers are yellowish green, on short spikes, close to the end of the twigs. The black walnut blooms in the spring (April to June).

Fruiting Habits:
The fruit is a round nut, 1 to 1.6 inches in diameter (2.5-4 cm), containing a tasty, oily seed, ripening in the fall (September-October). It is surrounded by a very hard thick shell. The trees start producing seeds when they are about 20 years old.

Culture:
The black walnuts are difficult to transplant because of their long tap root. They secrete a substance (juglone) that prevents close-by plants to grow.