The International Horticultural Expo opens in the Chinese capital later this month, but it's not the first time the country has hosted the event. The city of Kunming, the capital of southwest China's Yunnan Province, was given the honor in 1999. Two decades later, Kunming remains one of the country's greenest cities, but it has also become a major player in the Asian flower trade. Xu Xinchen has more.

This pair has been selling flowers in Kunming's Dounan International Flower Center for over a decade. Their specialty, all different kinds of Chinese roses. On a good day, some 2,000 flowers can be sold on site plus another 10 thousand mailed out to customers elsewhere in China after nightfall.

MA FENGMEI LOCAL VENDOR "I do not have any tricks. Just to be honest, only quality can help retain customers."

Ma and her husband are just one of the thousands of vendors here. As China's largest flower trading center, sometimes regarded as Asia's largest, 70 percent of flowers sold in China come from Dounan. And, the center sold almost 7 billion flowers last year. While flower growing has deep roots in the region, the boom came after the 1999 World Horticultural Expo held in Kunming, an opportunity that let more people from both home and abroad know more about the flowers of the city.

BAO GUIKUN, GM YUNNAN EXPO TOURISM SCENIC INVESTMENT & MANAGEMENT "The 1999 Expo helped the world learn more about horticulture in China and sell Chinese flowers and plants globally. And, it has indeed helped the tourism industry, a nice stream of income."

The 1999 Expo park in Kunming still attracts two to three million visitors a year. The retail market for local flowers also sees benefits, the inflow of tourists visiting Dounan flower center has maintained a double-digit growth rate, reaching over 1.1 million last year. Nevertheless, the real game starts after nightfall, when the wholesale session starts.

XU XINCHEN DOUNAN INTERNATIONAL FLOWER CENTER "Every evening, some 20 thousand buyers rush into the market during its wholesale session. Millions of flowers will be sold within the first hour."

It does not end there. In 2015, a brand new electronic trading center was established in Dounan. The system uses a similar mechanism to flower auctions in the Netherlands, starting from a higher asking price and bidding for a lower price. The auction starts in the afternoon and each deal will be settled within five seconds.

ZHANG RUI, DEPUTY GM DOUNAN FLOWERS E-TRADE CENTER "Fresh cut flowers are perishable commodities and trading speed is very important. If the trading takes so much time, fresh flowers will not reach the end customers fresh."

Zhang also says that the firm is already developing mobile applications to allow people outside the region to participate. The goal is to improve logistics and standardize flower trade in China. While the Dounan International Flower Center is Asia's largest and the world's second largest by volume, only 10 percent of Dounan's flowers reach overseas markets. Experts say the challenges facing Chinese flowers are logistical hang-ups and the lack of quality standards that can compete with their Dutch and German counterparts. Xu Xinchen, CGTN, Kunming.