Good lawn care involves far more than simply watering, feeding and mowing your grass. To achieve a truly vibrant, green and fully healthy landscape, you have to use a number of other tools to combat sometimes-unseen troubles such as poor drainage or mold growth around the roots. Dethatchers and aerators both work on these subtler lawn troubles, but perform very different tasks in the quest for a healthy lawn.
Thatch is a layer of dead grass, roots, leaves and debris that accumulates at the base of your lawn over time. It builds up from falling leaves or mowing without raking afterward. There is always some thatch on your lawn, but buildup thicker than 1/2 inch can lead to water and food sitting on the soil surface instead of penetrating to the grass roots where it is needed. Thatch also provides a breeding ground for insects.
Most lawns need dethatching every other year, in the early spring for warm-season grasses and in early to mid fall for cool season grasses. A dethatcher, also known as a vertical mower, features vertical blades instead of the traditional horizontal blades of a lawn mower. As you work across the lawn, the knives slice up the thatch and pull it up away from the soil and to the top of the lawn. Mow in one parallel direction, and then run the dethatcher perpendicular to your original path. Set the blades so that they tear up at least the top half of the thatch layer. Rake up the thatch you chop up and dispose of it like you do leaves in the fall.
All dirt is not created equal, and the thickness of the soil in your lawn can have a serious affect on the health of your grass and plants. Thick soil, especially clay soil, is slow to absorb water and nutrients, often leaving plants suffering from lack. This type of soil can also lead to flooding and, as the water sits on the surface instead of sinking into the soil, become a breeding ground for mosquitoes and other insects.
An aerator is a tool that penetrates the soil, creating small holes that allow food and water to sink through even the thickest soil and into the roots of the plants. The holes also encourage more airflow around the roots to prevent mold buildup. Lawns should be aerated generally once per year (in late summer or early fall), though some with extremely thick soil (or inches of thatch buildup) may need it twice per year. The aerator will produce holes about 3/4 inch wide and 3 inches deep. Always aerate on moist, but not soaked, soil. The small pieces of removed soil can be raked away or simply left on the surface to naturally break apart with rain and watering.
Finding the Tools
You can rent or purchase both dethatchers and aerators from garden centers and home improvement stores. You can also hire a professional to do the job for you, if you are unsure about how to properly use the tools. If you have any questions, consult a professional before you accidentally harm your landscape.