Olive trees are as hardy as their reputation suggests. They can withstand high temperatures, low-fertility soil and extended periods of drought. However, in order for an olive tree to produce exceptional fruit, it does need to be watered intermittently during the growing season. An olive tree can survive on no supplemental watering at all, but during the hottest months of the year it may suffer from drought stress if not given supplemental water periodically.
Water newly-planted olive trees whenever the top inch or so of the soil dries out. Apply the water all around the planting area and be sure that the soil is moist to the depth of the seedling's roots.
Give your olive tree 4 to 5 inches of water once monthly. Apply the water all around the olive tree's root system, which extends several feet beyond the tree's drip line.
Monitor your olive tree for signs of drought stress, such as wilted leaves or less-than-usual shoot growth, especially around fruiting time. When you notice these signs, water your olive tree with 4 to 5 inches of water.
Water your olive tree with 2 to 3 inches of water after any fertilizer application.