Since the beginning of civilization, a branch of the olive tree has been an emblem of peace and its oil, a symbol of abundance. A mature olive tree is hardy outdoors to 14 degrees. Olive trees ripen best in relatively dry climates with hot summers and moderate winters. However, an olive tree also grows easily indoors in a pot, maintained at 6' in height or less. Full sun, well-drained soil, and a warm spot in the garden will increase the chances of ripening a crop in marginal areas. Enjoy the creamy white flowers in May and the long graceful evergreen leaves. An Olive tree is slow growing and can live for a thousand years. USDA Zones 8-10.