A lawn aerator is a necessary part of lawn maintenance. Lawn aerators allow water and nutrients to sink below the surface of the lawn to increase your lawn's health. Lawn aerators are simple devices that attach to the back of a lawn tractor and poke tiny holes into the lawn's surface. A lawn aerator is basically a spiked roller, about 3 to 4 feet wide, and weighing up to 100 pounds. Lawn aerators come in two styles - spikers - which poke small holes in the soil; and in pluggers - which drive into the soil and pull out small divots about 2 or 3- inches long. A plugger is somewhat messier but is much better for your lawn. You should aerate your lawn at least once per year, but ideally twice - once in the spring (as soon as the ground is dry), and again in mid or late fall.