Fertilizing your lawn is an integral part of maintaining its health. Good fertilization practices feed the lawn by improving the soil. Good soil provides a place for vigorous root growth and is rich in microbiotic life, which breaks down nutrients so the grass roots can take them up. Knowing when and how to fertilize your lawn ensures lush, green growth year after year.
Grass requires lots of nitrogen to grow strong, green blades, so most commercial lawn fertilizers have a high percentage of this element. Also needed are phosphorus and potassium, which support root growth, photosynthesis and reproduction. Grass that is adequately nourished is more pest resistant and competes more effectively with weeds.
When you fertilize your lawn, you should consider the type of soil you have. A soil test will give you vital information about pH levels and nutrients your soil lacks. Most types of grass prefer a pH that's close to neutral, so add lime to soil that has a low pH and garden sulfur if the pH is high. Other nutrients can be added as fertilizer.
Organic fertilizers, like aged manure and compost, improve soil quality by feeding worms, bacteria and fungi that feed grass at the roots. These fertilizers contain nitrogen, phosphorus, and potassium as well as other essential nutrients. Unlike many synthetic chemical fertilizers, organic materials are slow release and don't leach quickly out of the soil before the grass can take it up, which reduces environmental pollution. They are also safer for people and pets who play on the grass.
Fall is the best time to fertilize your lawn, usually in September or October before the ground has frozen. At this time, a slow-release nitrogen fertilizer is best, but the fertilizer should also contain potassium and phosphorus to support good root growth over the winter. In early spring just after the ground thaws, soil amendments like lime and sulfur can be added, and a light application of nitrogen if the grass looks sickly. Heavy nitrogen fertilizers in spring and summer can do more harm then good because they might encourage more weed growth than grass growth, and the sudden "greening up" they cause actually makes the grass shade the roots and prevents them from getting water.
When you mow, be sure to leave the grass clippings on the lawn. These return lost nutrients to the soil and improve soil texture. Feeding your lawn with clippings saves you money because you won't be throwing nutritious organic material in the trash, and it saves you the work of collecting and carrying bags of clippings around. If the clippings fall in clumps, use a rake to gently spread them over the grass.
If your lawn has brown or yellow spots, or just needs a quick perking up, coffee grounds are an effective fertilizer. In addition to giving your lawn nitrogen and other nutrients, coffee grounds attract worms that aerate the soil as they eat and feed the soil with their castings. You can save coffee grounds from your own kitchen, or coffee shops often give them away to gardeners for free. Coffee grounds can be applied every couple of months. Sprinkle the grounds over bad spots, sweep them in with a broom, and water the lawn.