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Southern California Black Walnut
Juglans californica
  
About Southern California Black Walnut (Juglans californica) 20 Nurseries Carry This Plant Juglans californica, the California Black Walnut, also called the California Walnut, or the Southern California Black Walnut, is a large shrub or small tree (up to 30 feet tall) endemic to California. Some authorities (e.g. the California Native Plant Society) combines this species with J. hindsii. This article uses the The Jepson Manual convention of species,. Juglans californica, generally found in the southern half of the state, can be either a large shrub with 1-5 trunks, or a small single-trunked tree. The main trunk can fork close to the ground making it look like two trees that have grown together, then diverged. It has thick bark, deeply channeled or furrowed at maturity. It has large, pinnately compound leaves with 11-19 lance-shaped leaflets with toothed margins and no hair in the vein angles. It has a small hard nut in a shallowly grooved thick shell that is difficult to remove. The Chumash Indians of the Channel Islands of California eat the nuts, however, they are not grown commercially for this purpose. A recent molecular analysis suggests that J. californica is sister to the remaining black walnuts (Rhysocaryon).

This is a great choice for wildlife gardens and especially for attracting birds, which eat the nuts and like to nest in the branches. Unfortunately, Juglans californica is now endangered in large parts of the southern portion of its natural range due to continued development. Hopefully native gardeners in southern California will help restore this important part of the ecosystem. Best to plant near an irrigated area, or naturally moister areas such as a stream bed, seep or canyon bottom. Toxins in walnut seeds will typically prevent other plants from growing under this tree, so don't try to put understory plants too near this tree.
Plant Description
Plant Type
Plant Type
Tree

Size
Size
50 - 75 ft tall
50 - 75 ft wide

Form
Form
Rounded

Growth Rate
Growth Rate
Moderate

Dormancy
Dormancy
Winter Deciduous

Flower Color
Flower Color
Yellow

Flowering Season
Flowering Season
Spring

Wildlife Supported
 
Very important wildlife plant - attracts many birds and small animals. Walnuts are an important food source.

Landscaping Information
Sun
Sun
Full Sun, Part Shade

Moisture
Moisture
Moderate - High

Summer Irrigation
Summer Irrigation
Max 1x / month once established

Nurseries
Nurseries

Cold Tolerance
Cold Tolerance
Tolerates cold to 20 - 25° F

Soil Drainage
Soil Drainage
Fast, Medium, Slow

Soil Description
Soil Description
Adaptable. Soil PH: 6 - 7

Common uses
Common uses
Bank Stabilization, Deer Resistant, Bird Gardens

Propagation
Propagation?
For propagating by seed: 22.5 wks. stratification ( USDA Forest Service 1974). Some fresh seeds may need only 2-3 mos.; thus germinating seeds should be removed and planted at periodic inspections.

Sunset Zones
Sunset Zones?
4, 5, 6, 7*, 8, 9, 10, 11, 14*, 15*, 16*, 17*, 18*, 19*, 20*, 21*, 22*, 23*, 24*

Natural Setting
Site Type
Site Type
Slopes, canyons, valleys, often near stream beds or washes

Climate
Climate
Annual Precipitation: 5.8" - 70.7", Summer Precipitation: 0.16" - 2.61", Coldest Month: 38.0" - 56.8", Hottest Month: 62.9" - 85.5", Humidity: 0.09" - 36.34", Elevation: -1" - 6720"

Alternative Names
Botanical Names: Juglans californica var. californica
Common Names: Southern Black Walnut, Southern California Walnut


Sources include: Wikipedia. All text shown in the "About" section of these pages is available under the Creative Commons Attribution-ShareAlike License. Plant observation data provided by the participants of the California Consortia of Herbaria, Sunset information provided by Jepson Flora Project. Propogation from seed information provided by the Santa Barbara Botanical Garden from "Seed Propagation of Native California Plants" by Dara E. Emery. Sources of plant photos include CalPhotos, Wikimedia Commons, and independent plant photographers who have agreed to share their images with Calscape. Other general sources of information include Calflora, CNPS Manual of Vegetation Online, Jepson Flora Project, Las Pilitas, Theodore Payne, Tree of Life, The Xerces Society, and information provided by CNPS volunteer editors, with special thanks to Don Rideout. Climate data used in creation of plant range maps is from PRISM Climate Group, Oregon State University, using 30 year (1981-2010) annual "normals" at an 800 meter spatial resolution.

Links:   Jepson eFlora Taxon Page  CalPhotos  Wikipedia  Calflora


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