If thatch is more than ½ inch thick, you should consider power raking. Take a core sample of grass and soil from your lawn. Measure the organic material sitting on the surface of the soil. It should not exceed ½ inch. Check several areas of your lawn, as build-up can be irregular.

Thatch is a layer of semi-decomposed grass and other organic material that accumulates above the soil faster than Mother Nature can absorb it. Thatch build-up is a normal occurrence and is not necessarily harmful to the lawn until it gets too thick. Poor mulching mower performance can be a big contributor to thatch build-up.

Thatch forms a barrier between soil and the water, nutrients and air required for a healthy lawn. It may also serve as a perfect breeding ground for damaging lawn diseases.

Soil should be moist, but not too wet. If the soil is too wet the grass could pull away. Best results are achieved when working in two directions. Adjust the depth of the flails under the machine so that they make contact with, but only gently skim the surface, and remove thatch. The flails should not make contact with the soil. Rake up or vacuum the thatch immediately.

Before you power rake, try to get most of the left over from fall leaves off the grass and trim to about to 3 inches. This will allow the power rake blades good access to the thatch without having to go through a wall of leaves.

Simply put the vacuum is a machine that sucks up all the thatch from a lawn after it has been power raked. It replaces the manual raking effort. However, it is not meant to remove excessive leaves or other winter debris from lawns, rocks, or flower beds. We still have to count on hand rakes or leaf blowers for those jobs.

Warm season grasses are better in late spring to early summer. Do not be in a rush to power rake if there is an early spring. Frost can be lurking below the surface which will reduce the benefit of your power rake. Because power raking does damage some healthy grass, it is important to power rake with enough growng season left for your lawn to recover. Although cool season grasses can be power raked in the fall, at least 30 days of growing season should be available following power raking for successful results.

Dethatching and power raking are both performed with the same machine with blade settings at different heights. If a lawn has excessive thatch and it is dethatched, an incredible amount of plant material will be ripped up from the lawn. Several pick up trucks of dead thatch can be created from an averaged sized lawn. Dethatching goes deeper and can cause more damage creating a lawn that is thin, and beat up. It is strongly recommended that you combine a dethatching with an overseeding/slitseeding and topdressing to help the new grass seed, get quickly established and stimulate the existing grass plants to recover from the dethatching.

Power raking is a much gentler way to remove the thatch, dead debris and crust that builds up on a lawn over winter. Power raking does not cause the damage that dethatching does, and so the lawn recovers rapidly and maintains it’s density.

Power raking and aerating are not substitutes for each other though lawns do experience some common benefits. Power raking removes excess organic debris from the lawn. Aerating is meant to reduce soil compaction and improve grass root development. (See related article on benefits or Core Aeration)