How much sun does California walnut need?

California walnut grows best in full sun conditions.

When does California walnut bloom?

California walnut blooms in March and April.

Where is California walnut native?

California walnut (Juglans californica) is native to CA, per the World Checklist of Vascular Plants (Kew).

What butterflies or moths does California walnut host?

California walnut is a larval host plant for walnut sphinx moth.

California walnut

Name: Pollinator Patch
Author: Pollinator Patch

Juglans californica

Last reviewed: September 2026

Toxicity unknown

California walnut (Juglans californica) is not listed by the ASPCA Animal Poison Control Center (opens in new tab) or the other sources we check, so we have no verdict for it either way. Absence from those lists is not a clearance. If your pet shows symptoms after eating any plant, call the ASPCA at (888) 426-4435.

Light

full sun

Water

low

Size

180"–360" H × 180"–360" W

Bloom

Mar, Apr

Native to

Pollinators

wind pollinated

Before you buy

Your city may pay you to plant this

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Browse plants for this ecoregion

Sierra Nevada Central California Foothills and Coastal Mountains Central California Valley Southern California Mountains Mojave Basin and Range Southern California/Northern Baja Coast

A multi-trunked deciduous tree with compound pinnate leaves, small green catkin flowers, and round walnuts in a thick husk. Often develops a broad, spreading, irregular canopy on dry foothill slopes and drops husks and nuts through fall, so it reads as informal rather than manicured.

Wildlife value

Host plant for walnut sphinx moth.

Nuts are an important food source for squirrels, woodpeckers, and jays, and the foliage hosts walnut sphinx moth caterpillars.

Common questions

How much sun does California walnut need?: California walnut grows best in full sun conditions.
When does California walnut bloom?: California walnut blooms in March and April.
Where is California walnut native?: California walnut (Juglans californica) is native to CA, per the World Checklist of Vascular Plants (Kew).
What butterflies or moths does California walnut host?: California walnut is a larval host plant for walnut sphinx moth.

Native range data from the World Checklist of Vascular Plants (Kew). Pollinator and host plant associations compiled from GBIF, iNaturalist, and published ecological literature.

If something looks wrong

Common plant problems, and what to check first

These come up on almost any plant. Each guide lists the likely causes in the order they are worth ruling out, with one thing to check before you act on any of them, and links to the source it came from.

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