When will the mandarin mature?

Ou mandarin is a traditional Chinese local citrus variety, which was listed as a tribute by the court in the Song, Yuan, Ming and Qing dynasties, and its cultivation history is about 2400 years. The ancients had the poem "there are all orange trees in the forest, and there is no lotus without water". It was designated as a special fruit for athletes by the Beijing Asian Games in 1990. So when will the mandarin mature?

When do ou oranges mature and harvest: winter (December to January of the Gregorian calendar)

Relevant ancient medical books such as "relics of Materia Medica" and "Dietetic Spectrum of living with rest" have introduced the medicinal value of ou mandarin, among which the Qing Dynasty "ou Cheng Bu" once stated: "people's precious ou citrus, with its ability to remove coal poison, is recommended as an example of meeting rare oranges, although they are worth two or three hundred, they will all be asked for." it can be seen that ou mandarin was already famous in Beijing and Tianjin at that time. In the Ming and Qing dynasties, because Oukan was resistant to storage and transportation, it could safely cross the frozen port of the Bohai Sea in winter, which became a noble food used by the upper class in Beijing and Tianjin at that time to relieve opium, and had a wide market.