"With Beijing planning for 45% greenery coverage by 2008, rooftops are starting to look mighty appealing:
According to statistics, the cost of removing and greening in megalopolises like Beijing and Shanghai, where land is as precious as gold, is startlingly ranging from 10 thousand Yuan to 50 thousand Yuan per square meter. Yet the roof greening is much cheaper, "at least no land cost thereof", said Wang Xianmin, secretary general of Beijing Roof Garden Association to the reporter. It is introduced that the cost for high-grade roof garden is no more than 500 Yuan per square meter, and the simple grass roof 150 Yuan per square meter. The price is still decreasing."
read more via China Economic Net