Ok . . .I'm a big advocate of longer is better for heat resistance on the summer that keeps the roots cool - photosynthesis etc. I have one client who insists on having her lawn mowed at 2" because it grows too fast other wise. This is as low as I will ever mow. Every other client I have is mowed at 3.0" or 2.5". I prefer 3.0" to 3.5" I have read a fair amount on this topic even to the point of contradictory statements by the same author stating that in the fall that turf is busy with the transition into fall storing energy to the roots and cutting it short will force the grass to waste energy to grow while it should be storing energy for the winter? Meanwhile in another part of the same book stating it's fine to drop the height in the fall? Then I have cleints telling me the grass is more resistant to snow mold and disease if cut short. My own personal experience has shown - healthy turf is longer grass even over the winter. Any input?