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Juglans californica

Juglans californica S. Watson

Southern California Walnut, California Black Walnut

Juglandaceae (Walnut Family)

Synonym(s): Juglans californica var. californica


USDA Native Status: L48 (N)

Southern California walnut or California black walnut is a multi-stemmed, 20-30 ft., deciduous tree or tall shrub with pinnately compound foliage becoming yellow in fall. Small to medium-sized tree, usually forked near base, with rounded crown.

First found north of Los Angeles in 1850 by the survey of the Mexican Boundary Commission, this species is now established by planting beyond its local range. It is often small and shrublike; in contrast, Northern California Walnut becomes a tall tree with larger nuts to 2" (5 cm) in diameter.


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Plant Characteristics

Duration: Perennial
Habit: Tree
Leaf Retention: Deciduous
Leaf Complexity: Pinnate
Breeding System: Flowers Unisexual , Monoecious
Fruit Type: Nut
Size Notes: Up to about 30 feet tall.

Bloom Information

Bloom Color: White , Green , Brown
Bloom Time: Mar , Apr , May , Jun


Native Distribution: Coastal CA from Ventura Co. south, e. to the foothills of the San Bernadino Mts.
Native Habitat: Streambanks, hills & valleys below 2500 ft.

Growing Conditions

Light Requirement: Part Shade
Soil Description: Poor, mesic soils.
Conditions Comments: Juglans californica can be single-stemmed with training. Juglans hindsii, found near former Indian encampments throughout CA, is doubtfully distinct from J. californica. J. hindsii is usually single-trunked and up to 50 ft. tall. It is used as a street tree and as stock for budding English walnuts.


Description: Plant nuts in fall or spring. If nuts are sown in spring, they must be stratified.
Seed Treatment: Stratify for 60-120 days at 34-41 degrees.
Commercially Avail: yes

National Wetland Indicator Status

Status: FAC
This information is derived from the U.S. Army Corps of Engineers National Wetland Plant List, Version 3.1 (Lichvar, R.W. 2013. The National Wetland Plant List: 2013 wetland ratings. Phytoneuron 2013-49: 1-241). Click here for map of regions.

From the National Organizations Directory

According to the species list provided by Affiliate Organizations, this plant is on display at the following locations:

Santa Barbara Botanic Garden - Santa Barbara, CA

Web Reference

Webref 30 - Calflora (2018) Calflora
Webref 37 - Calscape (2019) California Native Plant Society
Webref 3 - Flora of North America (2014) Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA.

Additional resources

USDA: Find Juglans californica in USDA Plants
FNA: Find Juglans californica in the Flora of North America (if available)
Google: Search Google for Juglans californica


Record Modified: 2022-10-06
Research By: TWC Staff

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