In a general sense, growing season refers to the time of year between the last spring frost and the first fall frost. This description is somewhat misleading, however, since a blueberry plant will not grow when the temperature is below 38°F (3°C), even though there is no frost. The latest ripening cultivars require a growing season of at least 160 days (Kender and Brightwell 1966). Some early and midseason cultivars may ripen their fruit in only 120-140 days, but areas with such short seasons are marginal for good, commercial production.