green roof greenroof_2. photo 1 photo 2 . green roof growing medium – what\u0027s so special about it! https://lnkdin/ebkntxh. img_preview. federal building. sedum seeds are very very very small, and so you should mix them with dry sand to aid sowing, mix 400 or so seeds with 1 or 2 eggs cup full of . denver public library green roof.