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Description

Native to the Mediterranean region of Europe, the Olive tree is one of the most widely valued trees around the world for its fruit, oil and landscape uses. These qualities have been long recognized throughout the Inland Empire and many mature trees can be seen in local landscapes that provide sculptural character and garden interest. It is a distinctive evergreen tree with an upright branching habit, 25-35 ft. tall, spreading 20-30 ft. wide; old trees often have stout trunks. Pale green foliage is a distinctive characteristic. Creamy-yellow flowers occur in mid spring and many trees produce heavy crops of green olive-type fruit that mature to black by fall.

The Olive is well adapted to many soil types, including calcareous, as well as sun, heat and summer drought. They tolerate heavy pruning to manage size and are sometimes clipped into formal and large scale topiary shapes.

Olives pose several challenges when planted in ornamental landscapes. Pollen from flowers is highly allergenic to many people, and large quantities of fruit ripen and fall each year and can stain pavement. As a result of these concerns, several low-flowering and non-fruiting cultivars are now available from nurseries including: O. e. Majestic Beauty' has thin pale green leaves with a light and airy canopy on a standard size tree. A few tiny fruit develop on this cultivar. O. e. Swan Hill' is one of the most popular non-fruiting cultivar that produces less than 1% of the average pollen of fruiting varieties. O. e. Wilsonii' (O. e. 'Fruitless) grows to standard sizes with narrow pale green leaves and an open foliage habit; it rarely produces mature fruit. A dwarf cultivar, O. e. Little Ollie' is a non-fruiting hybrid with a dense foliage habit that grows 6-8 ft. tall and as wide. The Little Ollie dwarf olive is described here.

Water Needs

The Olive tree is naturally adapted to the Mediterranean climate of the Inland Empire and in many instances can grow well with our seasonal winter rains. However, low amounts of supplemental water during the summer will help young plants grow more quickly and maintain good foliage character. 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. As shown in the chart below, 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 2

  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 to 2x 1x to 2x 1x to 2x 1x to 2x 1x to 2x 1x to 2x 1x to 2x 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" to 2" 1" to 2" 1" to 2" 1" to 2" 1" to 2" 1" to 2" 1" to 2" 0" to 2" 0" to 2"

Range of supplemental summer water: 7"-14"
Range of supplemental winter water: 0"-10"

 
0"-2"
0"-2"
0"-2"
1"-2"
1"-2"
1"-2"
1"-2"
1"-2"
1"-2"
1"-2"
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
Foliage Character: Evergreen
Habit: Upright, Spreading
Growth Rate: Moderate, Long-lived
Height: 25 ft. - 35 ft.
Width: 20 ft. - 30 ft.
Water Needs: Low 2
Foliage Color: Pale green, Olive green
Flower Color: Cream
Flower Season: Spring
Soil Adaptations: Well-draining soil, Loam, Deep soil, Clay, Calcareous soil, Alkaline soil
Exposure Adaptations: Heat, Frost, Aridity, All day sun
Function: Specimen, Shade Tree, Screening, Residential spaces, Parks and open space, Culinary use, Commercial spaces, Background plant, Courtyard and patio tree

Maintenance

Olives in the Inland Empire have begun succumbing to a new fatal disease (Xylella) that is evidenced by slow branch dieback over time. New planting of olives is no longer recommended. If you already have an olive in your landscape, many other, less serious, diseases also cause branch dieback, so do not necessarily give up if some of the branches begin to die back. If this occurs, prune back dead branches, cutting into areas of the branch that are clearly healthy, and sterilize the blade of the pruner or saw with rubbing alcohol in a spray bottle between each cut and when done pruning. Plan on minor early structural pruning to establish desired long-term form as either a multi or single trunk tree. Major pruning is best done in winter. Minor pruning can be done any time. Suckers (small sprouts) will grow from the base of the tree, which should be removed as soon as they are noticed, any time of the year. Select a fruitless variety if fruit is not desired, especially if it is being planted anywhere near pavement or a walkway. Individual branches of fruitless varieties will sometimes "revert" and begin to set fruit. Any growth on the branch beyond that point will also set fruit, so it is critical to remove "reverted" parts of branches as soon as they are noticed (D,S).

References

Associations

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