How much water does Quercus douglasii need?

Blue oak tolerates low water and does well in dry, well-drained soils once its root system is established.

What light does Quercus douglasii require?

This tree grows best in full sun and does not perform well in shaded conditions.

When does Quercus douglasii bloom?

Blue oak typically flowers in March, April, and May, with small catkins appearing as new leaves emerge.

What insects visit Quercus douglasii flowers?

Bees and beetles have been observed visiting the flowers, although like most oaks it relies mainly on wind for pollen transfer.

What growth form does Quercus douglasii have?

It grows as a single-trunked tree, often with a broad, rounded canopy in open woodland settings.

Is Blue Oak toxic to livestock?

The USDA PLANTS Database does not flag Blue Oak as toxic to livestock.

Is Blue Oak HOA-friendly?

Blue Oak is generally an HOA-friendly choice in the right placement, with moderate maintenance.

Blue Oak

Name: Pollinator Patch
Author: Pollinator Patch

Quercus douglasii

Last reviewed: September 2026

Quercus douglasii is a deciduous oak with blue-green foliage that grows well in full sun and tolerates low water once established, blooming from March through May.

Blue Oak (Quercus douglasii) is not on the ASPCA Animal Poison Control Center toxic plant list for dogs or cats (aspca.org (opens in new tab), last reviewed 2026-05-21). If your pet shows symptoms after eating any plant, call the ASPCA at (888) 426-4435.

The USDA PLANTS Database (opens in new tab) does not flag Blue Oak as toxic to livestock.

Light

full sun

Water

low

Size

300"–600" H × 300"–600" W

Bloom

Mar, Apr, May

Native to

Pollinators

bees, beetles

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 452 programs across 44 states, each with a link to the provider and the date we last checked it.

Find rebates in your area

Browse plants for this ecoregion

Coast Range Northwestern Forested Mountains Sierra Nevada Central California Foothills and Coastal Mountains Central California Valley Southern California Mountains Southern California/Northern Baja Coast

Blue oak is a stately native tree with distinctive blue-green foliage and a broad, rounded canopy. It grows slowly but can live for centuries, eventually reaching heights of 25-50 feet. This drought-tolerant tree adapts well to Mediterranean climate zones and requires minimal irrigation once established.

Growing Blue Oak

Grow Blue Oak in full sun and low water. Mature plants reach 300 to 600 inches tall and spread 300 to 600 inches wide. Expect moderate maintenance to keep it looking intentional in a front yard.

In an HOA neighborhood

Blue Oak is an HOA-friendly choice in the right placement. Maintenance level: moderate. Tidiness: 3 out of 5.

Works well in: street edge, mid zone.

Mature size (25-50 feet) may exceed HOA height restrictions
Acorn drop can create seasonal maintenance issues
May not fit smaller front yard spaces due to spread

Wildlife value

Blue oaks support numerous wildlife species, producing acorns that feed deer, squirrels, jays, and other animals. During spring bloom months, their catkins provide important early-season pollen for bees and beetles.

Common questions

How much water does Quercus douglasii need?: Blue oak tolerates low water and does well in dry, well-drained soils once its root system is established.
What light does Quercus douglasii require?: This tree grows best in full sun and does not perform well in shaded conditions.
When does Quercus douglasii bloom?: Blue oak typically flowers in March, April, and May, with small catkins appearing as new leaves emerge.
What insects visit Quercus douglasii flowers?: Bees and beetles have been observed visiting the flowers, although like most oaks it relies mainly on wind for pollen transfer.
What growth form does Quercus douglasii have?: It grows as a single-trunked tree, often with a broad, rounded canopy in open woodland settings.
Is Blue Oak toxic to dogs?: Blue Oak is not on the ASPCA Animal Poison Control Center toxic plant list for dogs (aspca.org).
Is Blue Oak toxic to cats?: Blue Oak is not on the ASPCA Animal Poison Control Center toxic plant list for cats (aspca.org).
Is Blue Oak toxic to livestock?: The USDA PLANTS Database does not flag Blue Oak as toxic to livestock.
Is Blue Oak HOA-friendly?: Blue Oak is generally an HOA-friendly choice in the right placement, with moderate maintenance.

These answers were drafted with an AI model from this plant's data. Verify care details with a local expert.

Native range data from vouchered herbarium specimen records and regional native plant society lists. 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 Blue Oak? 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

Planning a bed around it? Start a free plan with this plant

Not sure where to start? Take the 2-minute yard quiz