Whole Foods in Austin has had a few different living walls. I believe the first one was bromeliads above the escalators. They didn't do well, even with natural light coming in.
Have you considered living moss? I tried to capture the photo of the new store's living wall of moss and steel, but was unsuccessful. If you scroll through the photos on the second link below, the moss wall is #12.
http://gsky.com/whole-foods-au...
A moss wall over the escalator leading to the parking garage...#12 photo
http://impactnews.com/austin-m...
