Harvests in Burgundy generally begin in September. The winegrower decides alone according to the exposure of the plot and its grape variety. The weather also comes into consideration. The more experienced taste the grapes and assess their sugar and acidity levels in the mouth. The skin and pips are indicators of phenolic maturity, while the tannins and anthocyanins (coloring particles) give the wine its structure. Though some grands crus have a laboratory to assess their exact alcohol degree, tasting still constitutes a complementary tradition.