Quercus douglasii

Common Names

Blue Oak, Mountain Oak, Iron Oak, Mountain White Oak

Summary

Blue oak is a native California deciduous tree with blue-green leaves and pale gray textured bark, a compact to broad rounded crown, and a slow-growing, long-lived habit; it thrives on dry, well-drained slopes and rocky, hot, dry hillsides below 3,500 ft, commonly forming blue oak woodland or savannah stands; acorns are produced and serve as wildlife food.

It prefers full sun to partial shade and well-drained soils, with low to very low irrigation after establishment; propagation is by acorns with fresh seeds sown in fall or stratified for spring sowing; used in restoration projects and as an ornamental, ideal for bank stabilization and slope planting, and provides food and shelter for birds, bats, and caterpillars; drought-tolerant and low-maintenance, with irrigation kept to a minimum to avoid root diseases.

Lifecycle

Perennial

Height

20-66 feet

Spread

40-70 feet

Hardiness Zones

Zones 8

Sunlight Requirements

Ideally full sun to partial shade.

Soil Type

Dry, well-drained, rocky soil

Soil Drainage

Well-drained soils

Soil pH

6.0-8.0

Bloom Color

Yellow, Green

Bloom Time

Spring

Foliage Color

Bluish-green

Fall Foliage Color

Yellow, Orange, Pink

Leaf Lifecycle

Deciduous

Growth Rate

Slow growth; about 1–12 inches (2.5–30 cm) per year.

Seasons of Interest

Spring, Summer, Fall, Winter

Propagation Methods

Seeds (acorns), vegetative sprouting from root crown or bole after top-kill (coppice/sprout regeneration), grafting

Attracts Wildlife

Attracts butterflies, attracts birds