Ingredients

• A complete lawn fertilizer contains nitrogen, phosphorus and potassium. A balanced fertilizer -- such as a 10-10-10 one -- contains equal parts of these elements, while a fertilizer such as a 25-5-15 one is complete but not balanced. Meanwhile, a 25-0-25 fertilizer is neither balanced nor complete. An incomplete or unbalanced fertilizer still can be useful for your lawn if your soil does not need a particular nutrient. Collect a sample of your soil for testing at your local extension office, as the test results will indicate whether you can omit any of these elements from your fertilizer.
  
  

Purposes

• Lawn fertilizers containing nitrogen help lawns to remain green, thick and dense. Nitrogen actually is the most important nutrient for helping lawns grow. Potassium-containing fertilizers additionally help to make grass leaves sturdy, which makes your lawn more resistant to drought, infestation and wear. Fertilizers with a large amount of potassium actually are useful for getting your lawn ready for the winter season. Meanwhile, lawn fertilizers also help grass roots to stay strong through the use of phosphorus.
  
  

Label

• Various bits of information should be listed on a lawn fertilizer label. For example, the label should include the manufacturer's name and address and instructions on how to apply the fertilizer, according to the University of Minnesota. The label also should mention the trademark, net weight of the container's fertilizer, the nutrients included in the fertilizer and also the guaranteed minimum amount of plant nutrients in the product.
  
  

Forms

• Fertilizers for lawns exist in various forms. For example, you can select liquid, organic, synthetic or granular fertilizers. Granular fertilizers are dry and provide coverage for your plants for two to six months if they are the slow-release type. Fast-release granular fertilizers provide nutrients to your plants more quickly and are more appropriate in cold weather. Meanwhile, concentrated liquid fertilizers allow you to apply the fertilizer using a hose, nozzle and spray bottle.
  
  Chemically manufactured fertilizers, or synthetic types, release nutrients to your lawn quickly but do not last very long. Organic fertilizers are made up of once-living organisms and their byproducts. Those with manures tend to smell bad but can improve your lawn's texture and are longer lasting, according to Plant-Care.com.