Raking your lawn at the right time helps keep your grass healthy. This starts almost as soon as you lay the new lawn. Raking grass generally helps to remove dead material and debris. Vigorous raking can also help aerate the soil by gouging small troughs and holes into the earth. Some grass species requires raking at slightly different times of the year. Ideal raking time also depends on your regional climate.
Before throwing down any new grass seed on your freshly prepared lawn bed, rake over the soil. This creates pockets in the earth for the seeds to nestle into before germination. It loosens up the soil and breaks up any clumps of earth. Deeper raking might remove stray roots and rocks. When you lay your seed down, a light raking of soil over the top helps to cover them to a shallow depth. This also helps prevent birds from eating all of your seed.
Spring and Summer
Gardeners should avoid raking lawns in winter or whenever the grass and soil is wet. Light raking is acceptable when the weather starts to warm up and the grass dries out a little. In most cases, depending on your local climate, this means waiting until spring or early summer before removing leaves and debris. Power raking only suits dry lawns -- so summertime raking is best. Power rakes have more aggressive circular blades that cut right into the soil.
As grass dies and other material gets trapped among the blades a layer known as thatch develops. This is a tough strip of compact material that can strangle new growth and prevent nutrients from reaching the roots. When the thatch reaches more than 1/2 an inch thick, a rake helps to break the layer up. In this situation, you need to use a power rake. This means cutting down into the thatch to loosen it up and open up the soil to air and nutrients.
Moss growth can ruin the appearance of an otherwise well-maintained lawn. However, unlike thatch, moss doesn't tend to be solidly packed into the upper layers of the soil. Rake your lawn when you see evidence of moss growth. If moss growth is light, a gentle raking should be enough to dislodge most of the moss. Extensive or persistent moss growth calls for deeper raking or even the use of the power rake to hit the roots.