SelecTree: Tree Detail

PARADOX WALNUT
Juglans × paradox

Juglans × paradox Juglans × paradox Juglans × paradox Juglans × paradox Juglans × paradox Juglans × paradox Juglans × paradox Juglans × paradox

Photo Locations: San Francisco, CA, Napa County, CA and San Luis Obispo, CA

General Notes

A hybrid between Juglans hindsii × Juglans regia.

This is a hybrid between the Northern California black walnut (Juglans hindsii)  and the English walnut (Juglans regia). Originally created by Luther Burbank as rootstock for English walnut orchards.

Has Unpleasant fragrance.

Native to Horticulturally Created Hybrid.

A Juglans × paradox in Napa County is registered as a California Big Tree. It measures 51 feet high, with a trunk circumference of 287 inches and a crown spread of 77 feet.

Family: Juglandaceae

Tree Characteristics

Erect or Spreading and requires ample growing space.

Rounded Shape.

Has Deciduous foliage.

Height: 30 - 60 feet.

Width: 30 - 60 feet.

Growth Rate: 24 Inches per Year.

Longevity 50 to 150 years.

Leaves Pinnately Compound Odd, Green, Golden or Yellow or Orange, Deciduous.

Flowers Inconspicuous. green. Flowers in Spring. Has separate male and female reproductive parts on the same tree (monoecious).

Prolific, Brown or Mostly Green Nut, Large (1.50 - 3.00 inches), fruiting in Fall Edible.

Bark Dark Brown or Dark Gray, Furrowed or Smooth.

Shading Capacity Rated as Moderately Dense in Leaf.

Shading Capacity Rated as Moderately Low out of Leaf.

Litter Issue is Dry Fruit.

Tree Site Conditions & Constraints

Sunset Zones 5 - 9 and 14 - 20.

USDA Hardiness Zones 7 - 9.

Exposure Full Sun to Partial Shade.

Moist to Dry Soil.

Drought tolerant.

Loam or Sand Texture.

Highly Acidic to Slightly Alkaline Soil pH.

Seaside Tolerance is Good in Mild Zone.

Pests & Disease Information

Resistant to Armillaria and Verticillium. Susceptible to Aphids and Caterpillars, Mistletoe, Phytophthora, Root Rot and Sooty Mold.

Health, Safety & Environmental Concerns

Branch Strength Rated as Medium Strong.

Root Damage Potential Rated as Moderate.

None Known Health Hazard.

Biogenic Emissions considered Low.

Desirable Wildlife Plant.

Attracts Birds and Squirrels.

Not Deer Palatable.

Special Uses & Values

Riparian, Specimen, Shade Tree.

Cite this tree:
SelecTree. "Juglans × paradox Tree Record." 1995-2020. Aug 14, 2020.
< https://selectree.calpoly.edu/tree-detail/juglans-×-paradox >

This tree is not part of the SelecTree Nursery Connection. If you would like to see this tree listed, or know of a nursery that sells it, please contact us at ufei@calpoly.edu.