The answer to 'retaining wall thin grass' is that thin or sparse grass along a retaining wall is often caused by poor soil conditions, lack of sunlight, or competition from the wall itself. This can lead to an unattractive, patchy appearance in the landscaping.
Some common causes include the wall creating a shaded area that inhibits grass growth, the soil along the wall being compacted or nutrient-poor, and the grass competing with the wall's structure for resources. Solutions may involve improving the soil, increasing sunlight exposure, or replacing the grass with a more suitable groundcover.