False thatch is dead grass tissue that has not compressd into real thatch. It can easily be raked out. Real thatch usually has live plant tissue (green grass) in it and if a lot of real thatch is removed at one time (1/2" or more) you tend to damage the live grass especially if you are power raking. That is why core aeration is often recommended over power raking. The coring is less destructive to the live grass and when the dried cores are mowed back in, the soil on top of the thatch helps to decay it. The hole encourages deeper rooting. The deeper rooting helps encourage the roots to grow down out of the thatch and into the soil.
