Most lawns need to be fertilized every year, because they need more nitrogen, phosphorus, and potassium than soils usually contain. These three elements are the primary ingredients found in most lawn fertilizers. It’s important not to over-fertilize – you could do more harm to your lawn than good – and it’s best to use a slow-release fertilizer that feeds the lawn slowly. It’s also important to check the soil’s pH. Grass is best able to absorb nutrients in a slightly acidic soil, with a pH of 6.5 to 7.0. Acidic soil can be “sweetened” with lime; soil that’s not acid enough can be made more sour by adding sulfur. Have your soil tested periodically to see whether it needs more organic matter or the pH needs adjusting. If a professional service takes care of your lawn, make sure it takes these same steps to develop good soil. There’s no getting around it: your lawn’s health is only as good as the soil it grows in.