There's a lot of talk about "green walls" at the moment and it bothers me some:
(a) because as a Parks and Gardens guy I've seen what happens when the plants die. And they WILL die. All living things eventually die.
(b) because they're irrigated. Where there's irrigation there's LOTS of maintenance. Don't believe anyone who tries to sell you a "low-maintenance irrigation system"*. Uh uh. They exist in people's minds along with unicorns and four-leaf clovers.
(c) because they can be a distraction from the big game which is TREES. I know the suppliers of green walls will say their products are simply an adjunct to trees but there's a danger that in our increasingly tree-phobic society we'll come to see green walls as a nice, neat, no-mess alternative to trees.
Personally I would run a million miles from them. Too little benefit for too much work.** Especially in a hot, dry climate like ours.
London, England might be a different story…
* The real killer with green wall irrigation systems is that you can't easily check they're working. You have to use a cherry picker each time. If you don't, the first you will know you have a problem is that the plants four storeys up will be crispy brown(!)
** I'm talking about permanent green walls. Temporary installations such as site screening may be a different story.