Green Wall at London’s O2 – some plants are failing

Here are some shots of the green wall at the O2 centre in London’s east. While some of the plants are failing (sedums) I like the shape of this green wall and how it sits within the broader landscape. The main section of the green wall (front and sides) use some type of netted soil system – the rear of the wall is treated with ivy (probably pre-grown sheets) and a wall of bamboo is also used to conceal the works area behind the green wall.

Am unsure on the details of the plants that are failing but it seems it may be one or two species that are not performing. In general is it the plants that are located in the top bands so perhaps they are not getting enough water?