Overseeding Cool Season Turf

Overseeding existing fescue lawns keeps them thick, lush and green. The following factors are the most common causes creating a need to overseed: weed infestations, summer diseases such as brown patch and dollar spot, insect damage and drought. Unlike other grasses, fescue does not spread by rhizomes or its root system, but rather must be overseeded to keep it from becoming thin and clumpy.

Simply spreading seed over an area without first preparing the seed bed will lead to reduced germination and limited success of the overseeding. Therefore, preparation of the area produces better results and helps cultivate greater success. The process of overseeding begins with a simple mowing of the existing turf or vegetation to a height of two inches in height. After mowing, it is best to “break the soil”. Accomplished through mechanical means with either a verticutter or aerating machine, breaking the soil allows for good seed-to-soil contact, thus increasing the germination success.

When overseeding, it is important to also consider the type of seed and seasonal timing. Using certified seed guarantees the seed to be virtually free of weed seed and has a high germination percentage. Investing in a quality seed reduces maintenance costs once the seed germinates. The best time of year to overseed is between the first of September and the middle of October. Overseeding at this time of year gives the seed the cool fall season to germinate and the spring growing season to develop a root system before the summer weather conditions arrive.