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Quercus douglasii (Blue Oak)

Blue Oak, Iron Oak, Mountain Oak

Quercus douglasii, Blue Oak, Iron Oak, Mountain Oak, Tree with fall color, Fall color, Attractive bark Tree, California Native Tree
Quercus douglasii, Blue Oak, Iron Oak, Mountain Oak, Tree with fall color, Fall color, Attractive bark Tree, California Native Tree

Quercus douglasii (Blue Oak) is a medium-sized deciduous tree with a short trunk and a broad, rounded crown. The stout crooked branches are clothed with oval, shallowly lobed, bluish-green leaves, up to 4 in. long (10 cm). The foliage turns attractive pastel shades of pink, orange and yellow in the fall. Inconspicuous catkins appear in spring as the leaves emerge. The trunk and gnarled branches, with their light gray, shallowly checked bark provide architectural elegance and winter interest. The egg-shaped acorns, 1 in. long (2.5 cm), are a valuable source of food for small mammals and birds. Slow-growing, Blue Oak is fall- and drought-deciduous. It may retain its foliage year-round on moist sites or show a flush of new leaves after heavy rains. Native to California, Blue Oak is very common within its narrow range, dominating almost half of California’s oak woodlands. It occurs in valleys and on low slopes of the Coast Ranges and on low foothills of the Sierra Nevada. Great for bank stabilization and dry, rocky slopes, Blue Oak is highly drought tolerant and is able to grow in the poorest soils.

  • Grows up to 30-50 ft. tall (9-15 m) and 40-70 ft. wide (12-21 m).
  • Performs best in full sun to part shade in acidic, well-drained soils. Tolerant of a variety of soils as long as adequate drainage is provided. Requires little summer water (once a month). Drought tolerant once established. It is moderately resistant to salt spray.
  • Perfect as a specimen plant.
  • Keep an eye out for crown rot, mistletoe, armillaria, brown Rot, caterpillars, insect galls, California oak moth, gall wasp. Deer resistant.
  • Prune young trees for desired shape.
  • Propagate by seed. Fresh seeds sow in fall outdoors or stratify to hold for spring sowing.
  • Toxic to horses.
  • Native to Central and Southern California.

Requirements

Hardiness 6 - 9
Climate Zones 3, 3A, 3B, 4, 5, 6, 7, 8, 9, 10, 11, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24
Plant Type Trees
Plant Family Fagaceae
Genus Quercus
Common names Iron Oak, Oak, Blue Oak
Exposure Full Sun, Partial Sun
Season of Interest Spring (Early, Mid, Late)
Summer (Early, Mid, Late)
Fall
Winter
Height 30' - 50'
(9.1m - 15.2m)
Spread 40' - 70'
(12.2m - 21.3m)
Maintenance Low
Water Needs Low
Soil Type Clay, Loam, Sand
Soil pH Acid, Neutral
Soil Drainage Well-Drained
Characteristics Showy
Native Plants United States, California
Tolerance Drought, Deer, Salt, Dry Soil, Rocky Soil, Clay Soil
Attracts Birds, Butterflies
Garden Uses Banks And Slopes
Garden Styles Prairie and Meadow, Coastal Garden
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Alternative Plants to Consider

Quercus chrysolepis (Canyon Live Oak)
Quercus myrtifolia (Myrtle Oak)
Quercus velutina (Black Oak)
Quercus laurifolia (Laurel Oak)
Quercus phellos (Willow Oak)
Quercus hemisphaerica (Darlington Oak)

Recommended Companion Plants

Ceanothus cuneatus (Buckbrush)
Arctostaphylos glauca (Big Berry Manzanita)
Aesculus californica (California Buckeye)
Cercocarpus betuloides (Mountain Mahogany)

Find In One of Our Guides or Gardens

Roots of Life: Exploring the Diverse World of Trees
Green Canopy, Better World: Exploring the Benefits of Trees
Trees that Invite Wildlife to Your Garden
Spectacular Trees for Vibrant Fall Colors: A Gardener’s Guide
Quercus (Oak) – Pests and Diseases to Watch Out For
Grow Your Own Oak Tree: A Step-by-Step Guide to Planting Acorns
8 Compelling Reasons Why You Should Plant an Oak Tree
Native Oak Trees: A Must-Have for Your Landscape
Native Plant Alternatives to Quercus acutissima (Sawtooth Oak)
While every effort has been made to describe these plants accurately, please keep in mind that height, bloom time, and color may differ in various climates. The description of these plants has been written based on numerous outside resources.
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Requirements

Hardiness 6 - 9
Climate Zones 3, 3A, 3B, 4, 5, 6, 7, 8, 9, 10, 11, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24
Plant Type Trees
Plant Family Fagaceae
Genus Quercus
Common names Iron Oak, Oak, Blue Oak
Exposure Full Sun, Partial Sun
Season of Interest Spring (Early, Mid, Late)
Summer (Early, Mid, Late)
Fall
Winter
Height 30' - 50'
(9.1m - 15.2m)
Spread 40' - 70'
(12.2m - 21.3m)
Maintenance Low
Water Needs Low
Soil Type Clay, Loam, Sand
Soil pH Acid, Neutral
Soil Drainage Well-Drained
Characteristics Showy
Native Plants United States, California
Tolerance Drought, Deer, Salt, Dry Soil, Rocky Soil, Clay Soil
Attracts Birds, Butterflies
Garden Uses Banks And Slopes
Garden Styles Prairie and Meadow, Coastal Garden
How Many Plants
Do I Need?
Guides with
Quercus (Oak)
Not sure which Quercus (Oak) to pick?
Compare Now

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