I just came across this tutorial from Australian vertical garden company Lushe. The process involves stripping the walls down and covering with a thin layer of moist clay, into which seeds are pressed. Unfortunately grass doesn’t make a good vertical wall solution since air circulation is prohibited by the densely packed blades. It is however a stunning temporary display.

The image above is one part of an installation by artists Ackroyd and Harvey who have been creating grass walls since the 90s. Most famously they have created portraits using grass in various stages of life for its colour variations, much like a paint.