It largely depends on the strength of the roof. The stronger the better, although this would mean sacrificing profitable areas of any large development, and as each tower can only support a set amount of weight, I think the developers would rather the weight was spent on an extra inhabitable floor than a great green roof (unfortunately). On a smaller building, I think you’re looking mainly at flowers and pleasantries. What excites me the most is the thought of larger buildings that can support more weight going ahead and planting crops and even trees. That would be great.