Your lawn is a place where your kids and pets play and roll around, so using natural fertilizers is a much safer alternative to toxic, synthetic chemical fertilizers. Natural fertilizers improve your soil by nourishing earthworms and microbes that feed grass roots, and they help keep down pests and weeds by keeping your lawn strong enough to successfully compete with them.
Coffee grounds are a rich source of nitrogen that grass needs for healthy, green blades. Coffee grounds also attract earthworms to aerate the soil and fill it with worm castings as they eat. Save your own coffee grounds for small, light applications to problem areas. Coffee grounds can also be used to fertilize your entire lawn twice a year in the spring and fall. Many coffee shops and cafes give their coffee grounds away for free, which makes this an inexpensive choice of fertilizer. Apply coffee grounds at a rate of 10 to 20 lbs. per 1,000 square feet. Place the grounds in piles over the lawn, then toss them around with a shovel. Once the lawn is covered, use a broom to sweep the grounds off the blades into the soil, and water it in well.
Compost is a natural fertilizer made from decomposed organic material that provides nitrogen, phosphorus and potassium as well as beneficial microbes and fungi to your soil. Compost helps buffer the pH of acidic or alkaline soils. It's a slow-release fertilizer, which means it lasts a long time and nourishes your lawn as it needs it. Compost is available from garden stores, or make your own from kitchen scraps and yard waste. Composted animal manure is a smellier option that is also quite effective. Apply a couple of inches of compost to poor soil before laying grass seed, or spread it as described for coffee grounds.
When you mow your lawn, don't collect the cuttings and throw them away. Instead, leave them on the grass where they fall and let them settle in. Grass cuttings are a type of compost that enrich the topsoil. When you bag up grass cuttings and remove them, you're removing nutrients that need to be replaced with more fertilizing. If the cuttings appear in piles from the mower, just spread them evenly over the lawn with a rake to keep yellow spots from appearing under the piles. Set your mower to the highest setting to keep the clippings short and to help your lawn shade out weed seeds.
Garden supply stores offer a range of natural fertilizers for twice-yearly applications or for use before sowing seed or laying sod. These fertilizers are generally safe for people and pets, but check the label carefully to make sure they really are natural. These types of fertilizers usually look like little green pellets, and should contain a mixture of ground bone meal, corn meal, corn gluten, soy, alfalfa, blood meal, or feather meal.Apply these fertilizers the same way as described for coffee grounds. As with all natural fertilizers, expect to wait two or three weeks before seeing any results.