Does a green roof have to be mowed?
A sedum covered roof is naturally self limiting in size. Most sedums grow only a few inches tall. As mentioned above, it is also fairly self weeding, due to the inhospitable environment it offers to most weed species. An extensive roof planted with prairie grasses on the Ducks Unlimited National Headquarters in Winnipeg, Manitoba uses a controlled burn of its upper roof every three years to repropogate the prairie plants. The 16 inches of soil protects the building from any damage while the grass fire helps remove weed species and assists prairie species which need periodic fires as part of their life cycle.
