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: October 2026

California walnut (Juglans californica) is a perennial tree native to CA. It blooms in March and April. The flowers draw wind pollinated.

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

Cities and water utilities offer rebates for replacing lawn with native and water-wise plants. We track 459 programs across 44 states, each with a link to the provider and the date we last checked it.

Find rebates in your area

Picture natives in your own yard

Upload a photo of your yard and Patch Vision shows a rendering of it planted with natives for your region, like California walnut.

Try it with your yard

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.

Growing California walnut

Grow California walnut in full sun and low water. Mature plants reach 180 to 360 inches tall and spread 180 to 360 inches wide.

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.

See all plant problem guides

Ready to grow California walnut? Add it to your garden in Pollinator Patch to track it and get season-by-season care guidance.

Add this plant to your garden

iPhone app Android app