A man walks out of a flower market after buying a bouquet in Shanghai, on Feb 13, 2016.[Photo/IC]

The wholesale price of 20 level-B red roses rises from 15 yuan ($2.27) to 50 yuan two weeks before Valentine's Day. Li Kun, a wholesaler at the auction center, said, "If the weather turns colder, the price can even hit about 100 yuan."

From last Sunday to Thursday, Li sold 16,800 level-B red roses every day. Most of his clients are from provinces outside of Yunnan.

Zhang Li, manager of the auction center, said, "Our sales volume outside Yunnan accounts for 80 percent of the province's total fresh flower trade. Overseas exports make up the other 15 percent, mainly to Japan, Australia, Thailand and Russia."