To cut crab grass and other long stemed weeds, lower your blades so they are at the same level as the front of your deck. I did this on my Cub Cadet M48 Tank and it works perfect with the deck set at any height and using high-lift blades. This method eliminated any straglers that my mower otherwise would leave behind. You just have to be very careful about cutting areas that you know don't have any rocks or other objects that the blades might hit. But it did eliminate having to re-cut my yard. I'm curious as to whether anyone else has tried this with their mowers and what their results were..