The answer to 'retaining wall dying plants' is that there are several common causes, including poor drainage, soil compaction, and lack of sunlight. Symptoms may include wilting, discolored leaves, and stunted growth. Solutions can involve improving drainage, aerating the soil, and adjusting planting locations.
If the issue is due to poor construction or design of the retaining wall, it's best to call a professional landscaper or structural engineer to assess and make repairs. For minor issues, homeowners may be able to address the problem themselves, but it's important to identify and resolve the root cause to prevent further plant decline.