Grass needs adequate amounts of nitrogen, phosphorus and potassium. A soil test will indicate the percentages of these components that your grass needs. Your county agricultural extension service can test your soil and advise you on the best type of fertilizer for your lawn. Fall fertilization benefits lawns more than spring applications, helping to increase heat and drought tolerance and produce better root systems. Spring applications help to fortify grass plants for the upcoming growing season. Apply fertilizer to your lawn at eight- to 10-week intervals, and only apply it when the foliage is dry.
Homeowners can choose from a wide range of commercial chemical lawn fertilizers. These are labeled with three numbers for the amounts of nitrogen, phosphorus and potassium in the formula, listed as N, P and K percentages. Nitrogen is the most important component in lawn fertilizer, giving grass its green color and aiding in carbohydrate synthesis for energy and growth. The phosphorus in fertilizer aids photosynthesis, plant respiration and energy transfer and storage. The potassium in fertilizer helps plant to metabolize food and controls water absorption.
Most organic lawn fertilizers are made from animal manure or plant products. These products can contain varying amounts of nitrogen, phosphorus and potassium, so you must research carefully to determine the right type of fertilizer for your lawn. Cow manure, chicken manure, fish pellets, soybean meal, kelp meal and cottonseed meal are just a few of the compounds used as organic lawn fertilizers. These organic fertilizers release nutrients slowly into the soil and also improve the condition of the soil, including earthworm populations and microbial activity.
Too much nitrogen can cause "burning" of grass plants. Avoid burning your lawn by following your lawn fertilization schedule and not applying quick-release nitrogen products. Use a slow-release fertilizer to avoid burning problems. Organic fertilizers release their nutrients more slowly and are less likely to cause burning of plant structures.