The green wall needs simple maintenance, but deserves special attention regarding the following items:
Exposition to light
A light source must be quite close and the green wall must receive 12 hours a day minimum.
Watering of the green wall
Use a very reliable system for watering system, the wall can dry out quickly.
Removing Bad Weed
For an outdoor green wall, maintain monthly checks for weeds as they can over grow your valuable plants.
Apart from these simple tips related to plants and the green wall in general, remember that your green wall is based on a structure. So you have to check the frame regularly, but also the attachments that maintain it to floor and building.
Similarly, your watering system is to be completely checked at least once a year, imagine the state of your green wall if there was a water problem, whether due to a lack of water or too much water.
Also keep an eye on the yearly water and electricity consumption. A good green wall is balanced in its water and electricity consumption.