Question
How many times should a self mulching mower blade be sharpened before it become less efficient. The mower is about  8 yrs old. I'm using a thatching rake on lawn now & i'm raking up  a lot of dense dead STUFF under the grass (been several yrs since I raked this thoroughly).The STUFF I'm finding ,is the DULL BLADE CAUSING IT or lack of annual raking .The mower is 6.5 hp self propel/electric start. When using cutter, the grass sticks to the underside. Is this caused by the grass cuttings or the mower or the lawn itself?  .

Answer
Grass blades, if mowed with a certain regular frequency, will not contribute to thatch. Dead roots, crowns and runners are more likely to do so. The grass blades themselves contain very little solid material and is mainly water. If you mow high and mow frequently it should not be a problem. I recommend that blade is sharpened every year, but atleast every other year.