Hardiness zones
Sunset 8, 9, 11-24
USDA 9-11 (arid and semi arid regions only)
Landscape Use: Olive is a tree for Mediterranean, xeric, or oasis design themes, residential, commercial, or industrial plantings, not a good shade tree
Form & Character: Evergreen tree, open, rugged, glaucous, best as multiple-trunk tree
Growth Habit: Slow to moderate growth rate to 30' to 50' in height with near equal spread, profuse basal suckering is common
Foliage/texture: Small elliptic to lanceolate leaves with prominent midvein, gray-green above to silver white underneath due to tomentose hairs, medium-fine texture
Flowers & fruits: Male flowers yellow and in panicles, followed by smaller, greenish yellow female flowers, Spring, male flowers fragrant and allergenic, fruit is oblong, black to 1.5" long stains, must be leached to be edible, high oil content
Seasonal color: None
Temperature: Tolerant to 15oF
Light: Full sun
Soil: Tolerant of alkaline soil
Watering: Infrequent deep supplemental irrigation
Pruning: Removal of basal trunk suckers and water sprouts, crossing branches and misdirected limbs, raise canopy, poor shoot architecture. Thin canopy in late February as one way of reducing the number of flowers. High pruning maintenance, especially when young. Sometimes used as landscape topiary.
Propagation: Seed, cutting
Disease and pests: Scale, olive knot forms galls on twigs and branches, verticillium wilt
Additional comments: Easily transplanted. Many municipalities now require planting of non-flowering forms due to allergenic properties. Non-flowering cultivars include 'Swan Hill' and 'Wilsoni'. 'Little Ollie' (dwarf mutated hybrid of Olea europaea or a hybrid of O. verrucosa) rarely flowers and fruits. 'Bonita' and 'Majestic Beauty' produce only a few tiny fruit making them more desirable for landscape purposes.
Highly revered for fruit production within the U.S., especially in the central Valley of California. In Europe, olive is primarily grown for oil extraction. Cultivars most commonly employed for fruit production include 'Manzanillo', 'Mission', 'Ascolano' and 'Sevilano'.
Note: There are two chemical spray methods used to control olive fruiting in urban landscapes. First, fruit control may be accomplished via spraying the trees with auxin-derivative compounds (like the brand name Olive Stop) that are applied at the time of flower bud development to abscise flowers before they can mature, produce allergenic pollen and fruit. For this the application timing is very critical for effective control. Second, anti-gibberellin growth retardants (like the brand name products Embark and Maintain) which act to slow or stop all plant growth and development are sprayed onto the tree sometime before flower initiation in the very early spring (February in Phoenix) to prevent flower development. Application timing with this method is less critical, therefore it is often preferred by busy landscape management professionals. However, the long-term effects of annual applications of these anti-gibberellin growth retardants as a strategy to stop flowering will eventually cause a decline in tree vigor, increased sensitivity to environmental stress, and eventual death. Also, spray drift of anti-gibberellin growth retardants onto adjacent landscape plantings will cause similar foliar and growth distortions to these plants if proper precautions are not taken. A third non-chemical strategy is to prune olive tree canopies in February effectively removing flowering wood. This strategy will only lessen, not eliminate, olive flower/fruit production, but is environmentally safe.
