Finally, by climbing tall buildings, I’ve managed to photograph the roof of Chicago’s City Hall. Though inaccessible to the general public (or goverment employees with the exception of maintenance workers, for that matter), the 2001 vegetated roof retrofit was the City’s first official move to help reduce the urban ‘heat island effect’, reatin excess rainwater, and provide a bit of extra added insulation. This installation largely uses native grasses and locally raised sedum, a low-growing, drought resistant plant requiring little maintenance which forms a tough mat, is able to resist Midwest winters, and is nearly evergreen.
Also, the installation is an example of both intensive and extensive planting. Intensive gardens, consisting of larger plants, shrubs, and often trees, usually require a thicker layer of soil or growing medium, artificial irrigation, and moderate maintenance. Extensive gardens, consisting of ground cover, grasses, annuals/perrennials, grow in thin soil and are largely self-sustaining.
Now, if they can just get rid of all those machines up there.