California Native Plant Society
Tap map to see plants native to location
Add
Quercus douglasii
Please enter either the common name or the botanical name of any native California plant species to see it's plant record

Loading....
Blue Oak
  • Added Add to My Plant List
Quercus douglasii
  

Zoom To My AddressZoom To California Estimated Plant Range




About Blue Oak (Quercus douglasii) The Blue Oak is endemic to California and is found in foothills surrounding the Central Valley of California, the South Coast Range, North Coast Range and San Francisco Bay Area. It is also sometimes known as the Mountain Oak, and occasionally the Iron Oak. Blue Oaks are medium-sized deciduous trees growing up to 50-82 feet tall, usually with a somewhat irregularly-shaped crown, and a trunk 1.5-3 feet in diameter. The tallest recorded oak was found in southern Alameda County, at 94 feet The bark is light gray with many medium-sized dark cracks; from a distance, it can appear almost white. The name Blue Oak derives from the dark blue-green tint of its leaves, which are deciduous, 1.5-4 inches long, and entire or shallowly lobed. The blue color can be subtle but becomes much more evident when viewed next to one of the live oaks with whom it shares its range, which tend to have much greener leaves. The acorns are around an inch long, often with a narrowed base, with a moderately sweet kernel, and mature in 6-7 months from pollination.

Blue Oaks are beautiful but very slow growing trees. They usually only add a few inches per year. Plant on dry, well drained slopes. They prefer full sun but will tolerate part shade, especially when young. They can handle occasional summer water (1x per month).
Plant Description
Plant Type
Tree

Max. Height
16 - 82 ft (4.9 - 25 m)

Max. Width
30 ft (9.1 m)

Form
Upright, Rounded, Upright Columnar

Fragrance
None

Growth Rate
Slow

Dormancy
Summer Semi-Deciduous, Winter Deciduous

Flower Color
Yellow, Cream, Green

Flowering Season
Spring, Winter
Spring
Summer
Fall
Winter


Native Status
Native

Natural Setting
Site Type
Rocky, hot, dry hillsides and slopes usually below 3,500 ft. in the Coast Ranges and foothills of the Sierras, often in large stands of Blue Oak Woodland or Blue Oak Savannah

Sun
Sun, Part Shade

Elevation ?
6' - 11310'

Annual Precip. ?
7.8" - 71.1"

Summer Precip. ?
0.14" - 2.08"

Coldest Month ?
24.6° F - 56.2° F

Hottest Month ?
45.5° F - 80.0° F

Humidity ?
0.53 vpd - 27.98 vpd

Soil Description
Tolerant of a variety of soils as long as adequate drainage is provided

Soil PH
6.0 - 8.0

Drainage
Fast

Cold Tolerance(° F)
Tolerates cold to 0° F

Sunset Zones ?
1, 2, 3, 4, 5, 6, 7*, 8, 9*, 10, 11, 14*, 15*, 16*, 17, 18*, 19*, 20*, 21*, 22, 23, 24

Wildlife Attracted
A very large variety of wildlife are attracted to oaks. Many insects are attracted to Oaks generally, including the following butterflies which use Oaks as host plant: California Sister, Propertius Duskywing, Mournful Duskywing, Golden Hairstreak, and Gold-Hunter's Hairstreak.

Landscaping Information
Ease of Care
Very Easy

Water Requirement ?
Low
Extremely Low
Very Low
Low
Moderate - High


Popularity
Moderately Popular

Max. Summer Water ?
1x/month
No Summer Water
1x/month
2x/month
3x/month
1/week
Keep moist


Mulch
Organic with Rocks

Pruning
Young trees should be pruned for desired shape

Propagation ?
From acorns, although hybridization is common.  For propagating by seed: Fresh seeds sow in fall outdoors or stratify to hold for spring sowing. If started indoors or in glasshouse, stratify first for 1.5 mos. (USDA Forest Service 1974).

Common uses
Bank Stabilization, Deer Resistant, Bird Gardens, Butterfly Gardens

Nursery Availability
Commonly Available

Other Names
Common Names
Occasionally Iron Oak, Mountain Oak


Sources include: Wikipedia. All text shown in the "About" section of these pages is available under the Creative Commons Attribution-ShareAlike License. Plant observation data provided by the participants of the California Consortia of Herbaria, Sunset information provided by Jepson Flora Project. Propogation from seed information provided by the Santa Barbara Botanical Garden from "Seed Propagation of Native California Plants" by Dara E. Emery. Sources of plant photos include CalPhotos, Wikimedia Commons, and independent plant photographers who have agreed to share their images with Calscape. Other general sources of information include Calflora, CNPS Manual of Vegetation Online, Jepson Flora Project, Las Pilitas, Theodore Payne, Tree of Life, The Xerces Society, and information provided by CNPS volunteer editors, with special thanks to Don Rideout. Climate data used in creation of plant range maps is from PRISM Climate Group, Oregon State University, using 30 year (1981-2010) annual "normals" at an 800 meter spatial resolution.

Links:   Jepson eFlora Taxon Page  CalPhotos  Wikipedia  Calflora

Sign in to your Calscape Account X




Once signed in, you'll be able to access any previously saved plant lists or create new ones.

Email Address
Password

Sign In


Copyright © 1999-2014 California Native Plant Society. All rights reserved.