Last year 1m square metres of plant-covered roofing was built in France, as much as in the US, and 10 times more than in Germany, the pioneer in this field. In Paris 22 hectares of roof have been planted, out of a potential total of 80 hectares.
2013 May 10, Audrey Garric, “Urban canopies let nature bloom”, in The Guardian Weekly, volume 188, number 22, page 30