Although there are thousands of green roof studies and publications worldwide, few present long-term controlled experiments of green roof vegetations under changing conditions. This presentation will discuss the changes in vegetative type and cover over 10 years in a controlled green roof experimental set up in Toronto and the impact of maintenance regimes and supplementary irrigation. It will also describe a new research direction for end-of-life subsurface study of roots and growing media biochemistry in test beds with pre-vegetated sedum mats versus testbeds overtaken by spontaneous growth.