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Coast Live Oak
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Quercus agrifolia
  

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About Coast Live Oak (Quercus agrifolia) The Coast Live Oak is a beautiful evergreen oak that grows predominantly west of the central valleys, as far north as Mendocino County, and as far south as northern Baja California in Mexico. This tree typically has a much-branched trunk and reaches a mature height of 10-25 meters. Some specimens may attain an age exceeding 250 years, with trunk diameters up to three or four meters. It's form is highly variable, and younger trees are often shrubby. The trunk, particularly for older individuals, may be highly contorted, massive and gnarled. The crown is broadly rounded and dense, especially when aged 20 to 70 years; in later life the trunk and branches are more well defined and the leaf density lower. The leaves are dark green, oval, often convex in shape, 2-7 cm long and 1-4 cm broad; the leaf margin is spiny-toothed, with sharp thistly fibers that extend from the lateral leaf veins. The outer layers of leaves are designed for maximum solar absorption, containing two to three layers of photosynthetic cells. Flowers are produced in early-to-mid spring; the male flowers are pendulous catkins 5-10 cm long, the female flowers inconspicuous, less than 0.5 cm long, with 1-3 clustered together. The fruit is a slender reddish brown acorn 2-3.5 cm long and 1-1.5 cm broad and matures about 7-8 months after pollination (most red oak acorns take 18 months to mature). They will attract a variety of birds and butterflies.

The Coast Live Oak is one of the only California native oak that actually thrives in the coastal environment, although it is rare on the immediate shore; it enjoys the mild winter and summer climate afforded by ocean proximity, and it is somewhat tolerant of aerosol-borne sea salt. The coastal fog supplies relief from the rainless California summer heat. It is the dominant overstory plant of the Coast Live Oak woodland habitat, often joined by California Bay Laurel and California Buckeye north of Big Sur. Associated understory plants include Toyon, various manzanitas, and Western Poison-oak. Normally the tree is found on well drained soils of coastal hills and plains, usually near year round or perennial streams. It's also often found in rocky hillsides that capture and hold more moisture. It may be found in several natural communities including Coast Live Oak woodland, Engelmann Oak woodland, Valley Oak woodland and both northern and southern mixed evergreen forests. While normally found within 100 kilometers of the Pacific Ocean at elevations less than 700 meters, in southern California it occasionally occurs at up to 1,500 meters in altitude.

Coast Live Oaks are fairly easy to grow. Water 1x per week the first year after planting, decreasing to about 1x per month after the first year, until the tree is about 10 feet tall. After that, it's best to avoid direct summer water entirely. For best results, simulate the semi-riparian environment that Coast Live Oaks prefer by planting them near an irrigated area. They'll get the water they need by stretching their roots out to the wetter area, but they'll keep the area close to their trunk nice and safely dry. Once they get their roots into the wetter areas, they'll grow rapidly and stay healthy looking all year round. Coast Live Oaks prefer to have their roots shaded, so it's a good idea to surround young specimens with mulch, rocks, or smaller native plants that won't crowd out the young tree trees but will provide shade to the roots. The best mulch is a thick layer of oak leaves. Don't fertilize oaks. They'll amend the soil over time with their own leaves and build the natural mitochondrial fungus in the soil they need to thrive. Gradually, they become islands of natural fertility that improve the health of the nearby plants.
Plant Description
Plant Type
Tree

Max. Height
35 - 80 ft (10.7 - 24.4 m)

Max. Width
15 - 35 ft (4.6 - 10.7 m)

Form
Rounded

Fragrance
None

Growth Rate
Moderate

Dormancy
Evergreen

Leaves
Rigid, tough, smooth, cupped and spiny edged; holly-like

Flower Color
Cream, Green

Flowering Season
Spring, Winter
Spring
Summer
Fall
Winter


Native Status
Native

Natural Setting
Site Type
Coast live oak occurs in a number of natural settings over a large part of the state, usually below 3,000 ft.. It is often seen in valleys and slopes near (but not in) streams where it is the dominant species in live oak woodland. Chaparral or coastal sage scrub are frequently upslope, with riparian vegetation in the stream. In other areas it is found among numerous other tree species (including other oak spacies) as part of foothill woodland or mixed evergreen forest. It is occasionally found in native grassland savannahs.

Sun
Sun, Part Shade

Elevation ?
2' - 7280'

Annual Precip. ?
5.7" - 95.5"

Summer Precip. ?
0.14" - 3.04"

Coldest Month ?
36.8° F - 56.8° F

Hottest Month ?
58.0° F - 85.4° F

Humidity ?
0.30 vpd - 36.26 vpd

Soil Description
Tolerates a variety of soils but prefers a deep, well draining loam which it usually develops over time from leaf drop

Soil PH
4.0 - 8.0

Drainage
Medium

Cold Tolerance(° F)
Tolerates cold to 15° F

Companion Plants
A wide variety of species work as either understory or companion plants with Coast Live Oak, including Coyote Brush; California Buckwheat; Coast Sagebrush; Toyon; California Coffeeberry; Woolly Bluecurls; Snapdragon Penstemon; Fuchsiaflower Gooseberry; California Wildrose; Manzanita sp.; Ceanothus sp.; Salvia sp. and annual wildflowers including Poppy sp. and Chinese Houses

Wildlife Attracted
A great many birds, mammals, reptiles and invertebrates utilize oak trees and oak woodlands. Oaks are among the most important wildlife plants. The following butterflies 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
Very Popular

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


Mulch
Organic with Rocks

Pruning
Best to prune during July or August, when the trees are not normally growing, and when the dry weather is less likely to support pathogens that may attack the wounds. As much as possible, avoid pruning large limbs as this exposes the tree to possible infection and can take many years to recover. Avoid over-thinning interior branches or "lion tailing."

Pest Control
Oaks are susceptible to several pests and diseases including Gold Spotted Oak Borer and Sudden Oak Death. The best prevention for these maladies is to avoid moving firewood outside the area where it was grown and sterilizing pruning instruments after each use.

Propagation ?
Propagation by acorns is relatively simple. Best acorns sink in water, have a more or less even mix of green, yellow and brown color, and pop out of their caps easily. Plant acorns on their sides, at depth of 1.5x its diameter. Keep moist until germinated and at least 3-4 weeks after the seedling pushes out of the ground.  For propagating by seed: Fresh seeds sow in fall outdoors or stratify to hold for spring sowing. (USDA Forest Service 1974).

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

Nursery Availability
Commonly Available

Other Names
Common Names
California Live 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

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