Timing and method both affect the quality of an olive oil greatly. The ideal time to harvest is late November-January, after the trees have had a long stretch of hot weather in which to grow.
Hand-picking or ‘threshing’ the olives ensures that the olive won’t be bruised or damaged, which industrial picking machines can do. The olives should gathered in nets and carefully bagged on their side so as not to spoil them. Industrial pickers drop the olives into vast buckets, which puts pressure on the olives and can crush them before they arrive at the mill for pressing.