Manfred Köhler is member of the FLL guideline group, indoor Greening (published 2011).
Own researches are done in cooperation with realized indoor greening projects, like Tropical Island near Berlin.
Currently indoor planting tests had started in Neubrandenburg with different felt layer.
Impresssion of indoor greening sites in the University of Applied Sciences (2012)
A vertical indoor greening tray system, installed in the entrance area of our University; the plant performance is currently tested.