In the past it was thought that you should lower your mower height for the last cut of the season. Taller blades means better photosynthesis. Roots and rhizomes continue to grow over winter and a little more help from sunlight could be a boost the plants need for exceptional growth. Keep your cool season grass cut at or above 3 inches. Our mowing height is set at 4 inches and we have found that leaving the grass taller over winter benefits the plant. Wait till Spring to lower the mower the first cut then raise it a half inch each week until you get to your normal mowing height.
See lawn mowing for more tips.