Culture
Winter hardy to USDA Zones 8-10 where it may be grown in fertile, medium moisture, well-drained soils in full sun. Best performance occurs in Mediterranean-type climates (hot-dry summer and mild-wet winter) such as California. Common olive trees are drought tolerant once established. Trees are not winter hardy to the St. Louis area where they are best grown in greenhouses or conservatories. Growing them as houseplants or in containers that must be brought indoors in winter can be difficult. When containers are brought indoors for winter, they should be placed in cool conditions (40-50 degrees F). Trees need at least two months of sub-50 degree F. winter temperatures in order to produce flowers.
Noteworthy Characteristics
Olea europaea, commonly called common olive, is an evergreen tree that is native to the Mediterranean region. It typically grows to 20-30’ tall with a rounded crown. Young trees have smooth gray bark, but trunks and branches will gnarl somewhat picturesquely with age. Opposite, elliptic to lance shaped leaves (to 3” long) are gray-green above and silver-green beneath. Very small white flowers bloom in panicles (to 2” long) in summer on stems from the leaf axils. Flowers are fragrant. Flowers give way to oval green drupes (olives to 1.5” long) which ripen to black. Each olive contains a single pit. Olives from this species are commercially harvested as eating olives and for production of olive oils. A large number of different commercial varieties are grown for fruit production.
Olive trees are one of the first trees to be cultivated (2500 B.C. in Crete). An olive branch is a symbol of peace.
Genus name comes from the Latin name for olive.
Specific epithet means of Europe.
'Sevillano' and the cultivar, ‘Manzanillo’, produce about 90% of the olives grown in California. Valued for its large, blue black fruits (almost 0.5 oz.), it is commonly known as Spanish Queen when pickled. It is a small slow growing tree with fine, dark gray green, evergreen foliage and a gnarled trunk. It grows 15 to 30 ft. tall and 12 to 25 ft. wide. ‘Sevillano’ is self-fertile but will produce more if other cultivars are nearby and it may be used as a pollinizer for ‘Manzanillo’. 'Sevillano' is very sensitive to cold.
Problems
No serious insect or disease problems. Olive knot, verticillium wilt and root rot. Watch for scale.
Uses
Where winter hardy, they can be grown as ornamentals and/or for fruit production. Climate must be proper for good fruit production. Where not winter hardy, grow in greenhouses or conservatories or in containers that are overwintered in cool indoor locations.