World Horticultural Expo 2011, Xi'an.
http://en.expo2011.cn/
The World Horticultural Expo will be held in Xi'an (Shaanxi Province, People's Republic of China) from 28 April, 2011, until 22 October, 2011. That's a six month window of opportunity for any keen gardeners or horticulturalists who would like to see amazing displays of the latest plants and plant technologies in extensive purpose built grounds.
Xian, Shaanxi Province
map