Having a garden roof can make your city environmentally friendly. Many cities in America are incorporating greenroofs into their planning because planting a roof garden can reduce heat, increase city biodiversity and decrease stormwater runoff.
The stormwater runoff can be problematic in cities where rain water is funneled by streets and parking lots directly into streams, carrying with it chemicals and debris and increasing the risk of flash floods.
Olyssa Starry, a graduate student at the University of Maryland at Baltimore County, says, “the plants on the greenroof can absorb some of this water like a sponge being saturated.”
If all the roofs were greened, the city could save million gallons of water per year.