This usually occurs from winter rains. An alternative to overseeding bermudagrass lawns is to spray green turf paint over the bermuda after it turns brown in the fall. For overseeded lawns, the biggest mistakes that are done include improper mowing frequency and improper mowing heights. Annual ryegrass should be mowed to 2.5 inches when it reaches 3.0 inches. It does not like to be shorter than 2.0 inches.
Many people try to make annual darker in color by applying nitrogen in sometimes excess amounts.
This can cause fertilizer loading in the soil. Do this four weeks after the first mowing and again every 21 days afterwards. Application of iron at 2-4 ounces per 1000 ft 2 once a month will keep things green, especially when the soil is cold and wet. For high elevation areas 5500 and above, or where cool season grasses are used year round, fall is the best time to dethatch Kentucky bluegrass turf and follow with fall fertilizations. September is the best time to dethatch KBG turf in Payson, Winslow, Holbrook, and Flagstaff.