Olives trees (Olea europaea L.), hardy in U.S. Department of Agriculture plant hardiness zones 9 through 11, are drought-tolerant trees after established. An established tree can withstand a lack of supplemental watering even in arid inland areas. Young olive trees should be watered frequently as they become established. If you wish to boost olive growth, be prepared to water your trees with heavy, deep waterings.
Water newly planted specimens each day for the first two weeks. If possible, use drip irrigation system placed near the root ball.
Cut back the watering to once per week after the initial two weeks. Move the drip emitter at this time so it is a couple of inches farther from the trunk.
Reposition the drip emitter several inches farther away in the trunk every other week. Quit re-positioning the drip emitter when it is positioned beneath the canopy drip line.
Continue to water your tree at least 1 inch each week for the first couple of months.
Cut your watering to 1 1/2 ins each two weeks after the olive tree’s first couple of months in its site.
Increase watering to 2 inches every two weeks from the late spring and late fall.
Decrease watering to 1/2 inch of water every two weeks in November, then stop watering for the winter.
Resume watering in spring, starting in March.