You can find flourishing olive groves, of one or another of the many varieties of olives, through the world between latitudes 25 and 45 degrees, and below 4,000 to 5,000 feet in altitude-in both the northern and southern hemispheres. They seem to do as well in Argentina as in Algeria, in Texas as in Tuscany.
Once established, olive trees are marvelously hardy and drought-tolerant. Most varieties require at least 140 hours each winter at or below 45 degrees F. And most varieties are not hardy below 14 degrees F-though frost damage can be avoided by lying out smudge ports or drenching the plants with water which forms a protective ice coating. Young trees (seedlings, shoots, or "whips") are more susceptible to hard freezes than more established plantings. At Sandy Oaks we like to sell our trees after they have been hardened of for one Texas winter in our plant sheds here.
Olives do well in poor and inhospitable soils-and even where no soil at all is apparent, as in crevices of boulders along the Cornices of France and Lebanon, in the alluvial gravels of the Moroccan Atlas and the Australian outback, and in the sandy soils of, well, of Sandy Oaks Olive Orchard, for instance where less than 9.5% or organic matter enriches the so-called topsoil. The key element of olive culture is to ensure that planting sites are well drained.
Because they need drainage above all else, it's not usually necessary to irrigate olive trees to ensure their survival. In fact, more olive trees are damaged by over watering than by drought. However, it is generally accepted that olive trees produce more olives and tend not to bear alternate years when irrigated. Saundra has found that misting her seedlings and shoots encourages their initial growth and that drip irrigation in the orchard helps to keep them healthy. Olive trees thrive in the desert dunes of the Mahreb and the parched plains of transmountane Queensland. They're salt-tolerant, too, with century-old specimens often rooted amongst the sea-sprays that wash the cliffs of Sicily and Greece. In fact, olives grow well in ph ranges from 5.5 (very acid) to 8.5 (very alkaline).