Orange trees are classified into four main groups based on general fruit characteristics. This includes common or round oranges, blood oranges, navel oranges and acidless oranges. They are also classified by season of maturity. Early-season oranges mature in September or October. Mid-season oranges mature in November to early January. Late-season varieties mature in February or March. Finally, oranges are classified as either seedy or seedless.
During the first and second season after planting, focus the tree's energy on growth. Remove any fruit that sets during this period. In terms of total fruit yield, the first few crops will be a small fraction of the crop of mature orange trees. Also, the quality of young orange fruit is commonly inferior. Expect the taste of fruit to become increasingly less bland as the tree matures. Orange trees typically attain their full height and diameter 10 to 14 years after planting.
Overall yield varys significantly by age, cultivar, location and individual growing conditions. Early-season oranges such as Hamlin can produce 20 to 25 lbs. of fruit their third season, and approximately 200 to 250 lbs. of fruit when mature. Navel oranges, a large, mid-season fruit, may generate 10 to 15 lbs. of fruit in their third season, but 100 to 150 lbs. of fruit when fully mature. Orange production in most varieties will peak the 10th season after planting.
Sweet oranges mature gradually on the tree about nine to 12 months after flowering, most commonly between October and January. Oranges will not change in taste, color or size after harvest. Peel color does change as fruit matures, but it is not a good indicator of ripeness. Rather, color change is most strongly correlated with climatic changes. The best indicators are sugar-to-acid ratios. The easiest way for home growers to determine ripeness is by sampling oranges once the fruit reaches an acceptable size. Don't wait until the fruit wrinkles; this is a clear indication it is overripe.