Answer: Dethatching removes dead grass stems and surface roots. It's normal for lawns to have a layer of thatch, but when thatch builds up to more than one-half an inch, it can cause problems with water penetration (and fertilizers, too, for that matter). If you have a fertilizing service, call and ask their opinion. It would be a shame to dethatch immediately after they've applied fertilizer - you'd be effectively removing the fertilizer when you rake up the debris that accumulates after using a power dethatcher.
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