A roof garden is a special kind of garden that is planted on top of a roof! Special kinds of plants and soil are used so that the garden can withstand the wind and cold temperatures. People like to create roof gardens because they can provide extra beauty and greenery for people to enjoy. They can also help reduce the amount of stormwater runoff, which means that rain water is less likely to cause flooding or other problems. Roof gardens can also provide extra insulation, which can help save energy costs in the wintertime.