The 200-square meter wall near Marylebone Road -- one of the UK capital 's grimiest thoroughfares -- is being monitored by Imperial College , London . Green walls turn dreary urban facades into vertical banks of color . As well as aesthetic qualities , vertical gardens may also improve air quality . The most common type of garden is a raised bed with an array of plants growing on it in the form of a grid or lattice.
Green walls turn dreary urban facades into vertical banks of color . As well as aesthetic qualities , vertical gardens may also improve air quality . The most common type of garden is a raised bed with an array of plants growing on it in the form of a grid or lattice.