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The Coast live oak is one of the most distinctive and widely recognized trees native to many parts of the Inland Empire. Over time it can reach specimen sizes, 25-45 ft. tall and 30-40 ft. wide, and function as the cornerstone of residential and commercial landscapes. It is widely valued for its rich green foliage, bold branching character and value for wildlife.

Young Coast live oak trees have proven to be highly adaptable to ornamental landscapes and will grow relatively quick when planted in well-drained soils with low to moderate amounts of supplemental water. This tree combines well with many California native species described in the Coast Live Oak Palette and needs ample space to mature when planted in residential gardens.

Water Needs

The Coast live oak grows well in the Inland Empire when planted in well-drained soils with normal winter rains and low amounts of supplemental water. Young oaks will grow faster and become larger with regular moisture through the spring growing season, then monthly deep watering is recommended to maintain good character through summer and fall. Mature trees often have more extensive root systems to capture soil moisture from winter rains, however, low amounts of summer irrigation outside the drip line can help sustain the transpiration needs of the larger leaf surface area of these trees.

The chart shown below provides a baseline guide to the monthly irrigation schedule and volume of supplemental water needed to maintain healthy growth throughout the average year. It should be noted there are several months indicated by an asterisk (*) when winter rains can provide sufficient moisture and irrigation is not needed.

Irrigation Schedule and Graph

Low Water Use Plants

Irrigation Schedule 1

  Jan* Feb* Mar* Apr May Jun Jul Aug Sep Oct Nov* Dec*
Runs per Month 0x to 2x 0x to 2x 0x to 2x 1x 1x 1x 1x 1x 1x 1x 0x to 2x 0x to 2x
Inches per Run 1" 1" 1" 1" 1" 1" 1" 1" 1" 1" 1" 1"
Inches per Month 0" to 2" 0" to 2" 0" to 2" 1" 1" 1" 1" 1" 1" 1" 0" to 2" 0" to 2"

Range of supplemental summer water: 7"
Range of supplemental winter water: 0"-10"

  Jan* Feb* Mar* Apr May Jun Jul Aug Sep Oct Nov* Dec*
For more information on how to use this Irrigation Schedule and Graph, follow this link.

For information how to calculate your irrigation system’s schedule and precipitation rate, please follow this link.

Plant Properties

Plant Type: Tree, Native
Foliage Character: Evergreen
Habit: Low-branching, Dense
Growth Rate: Moderate, Long-lived
Height: 25 ft. - 45 ft.
Width: 30 ft. - 40 ft.
Water Needs: Low 1
Foliage Color: Dark green
Flower Color: Insignificant
Flower Season: Spring
Soil Adaptations: Well-draining soil, Deep soil, Clay
Exposure Adaptations: Heat, Drought, Aridity, All day sun
Function: Wildlife value, Specimen, Shade Tree, Screening, Restoration, Parks and open space, Attracts butterflies


It is important to only prune Coast Live Oak during the warm, dry season (July - September) to avoid disease issues. Healthy trees generally do not need significant or hard pruning. Prune young trees to set a good branch structure to avoid the need for much pruning once the tree is older. Remove accumulated small dead branches every number of years once the tree is mature (3). Any significant pruning which will expose previously shaded areas to sun should be done at the very end of the pruning season (September), because bark will be at risk of long term damage from sun burn if exposed mid-summer (S).



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