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Description

The Engelmann oak can grow into a medium to large size evergreen tree, capable of eventually reaching 25-60 ft. tall and as wide. Native to Southern California, there are many heritage scale trees currently growing in gardens, parks and preserves that have been protected from urban development. This species has pale blue-green leaves and coarse bark character on trunks and large branches.

Engelmann oak comes from elevated mesas and foothill slopes of the San Gabriel Mountains in Los Angeles County, south to San Diego and into Baja California. It is occasionally a dominant tree within the southern oak woodland association, but more often grows in association with coast live oak. Similar to other native oaks in California, it has been widely removed for urban development and much of its original population has been lost. Preservation is often best achieved by avoiding grading, compaction and summer irrigation around existing trees, and preserving as much area and natural habitat conditions as possible.

The Engelmann oak is becoming more widely planted in recent years in the Inland Empire where it serves as a good canopy tree in residential landscapes as well as in parks and greenbelts. It requires well-drained soils and low amounts of summer irrigation once established.

Water Needs

Supplemental watering for the Engelmann oak should be scheduled mostly for fall and winter months with the goal of subsidizing the natural rainfall season during dry spells and drought cycles. Otherwise, normal winter rainfall that provides moisture from November through March is sufficient for established trees. Spring and summer irrigation should be minimal around established trees; this moisture is mostly beneficial for young trees until they are established.

The chart shown below provides a baseline guide to the monthly irrigation schedule and volume of supplemental water needed to maintain healthy trees 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"

 
0"-2"
0"-2"
0"-2"
1"
1"
1"
1"
1"
1"
1"
0"-2"
0"-2"
  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: Multi-trunk, Low-branching
Growth Rate: Slow
Height: 25 ft. - 60 ft.
Width: 25 ft. - 60 ft.
Water Needs: Low 1
Foliage Color: Pale green, Blue green
Flower Color: Insignificant
Flower Season: Spring
Soil Adaptations: Well-draining soil
Exposure Adaptations: Heat, Drought, All day sun
Function: Wildlife value, Specimen, Shade Tree, Parks and open space, Attracts butterflies

Maintenance

Prune young trees to establish good long term form in late summer (August-September). Mature trees generally do not require pruning unless it is to correct an issue or remove dead wood (3).

References

Associations

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