4 links have been added on this idea.
  1. Easy, just buy a stack of the modular trays and attach them. Buy them here… https://www.roofingsuperstore.co.uk/product/wallbarn-m-tray-modular-sedum-wildflower-green-roof-540mm-x-540mm.html

  2. I like the idea but would test it on a shed first. This article gives the low-down on the pitfalls.