Features

• Moss on your lawn doesn't actually kill grass; it merely occupies soil left vacant by dead or dying grass. Consequently, conditions that harm grass favor the spread of moss. Grass prefers pH levels in the six to 7.5 range, so it's best to keep pH within these margins.
  
  

Effects

• Soil pH below six is too acidic and may promote moss growth. Alternatively, raising the pH too high may promote moss growth as well. To test your soil pH, check with your local home and garden supply store--most outlets sell simple pH test kits.
  
  

Considerations

• Soil pH isn't the only factor that promotes moss growth across your lawn; soil compaction, excess shade, excessive watering and poor drainage can all favor the moss over the grass. Check for these other problems before assuming soil pH is the culprit, then test the soil pH if necessary.