The best time to overseed a lawn or repair thin and bare areas is fall. The cool nights and mild, shorter days provide the ideal conditions for seed germination. Seed is better able to retain moisture in these conditions, and seedlings will thrive without the extreme heat that occurs in the summer months.

When aeration is combined with a late summer or early fall reseeding, you double your benefit. Not only does the aeration help your existing grass, but disturbing the topsoil also gives your new seeds a great way to make contact with the earth to ensure better germination rates and a thicker more healthy lawn. By giving these seedlings a typically cooler fall and moist growing season, they will be well prepared for winter and a great spring to come.
 
You might be thinking, "Should I bother with overseed? My yard looks fine!" We at TPS Landscaping need you to rethink that for the sake of your curb appeal!
A lawn that is never overseeded tends to grow old. If it is consistently mowed, it doesn’t even have the opportunity to go to seed to propagate itself. The lawn will have to rely on rhizomes, stolons and tillering for growth. Eventually, an old lawn will have trouble maintaining vigorous growth, competing with weeds and dealing with other lawn stresses. Also, new varieties of grass species are entering the market every year so it is beneficial to integrate grass that may be resistant to drought, disease or insect damage into a lawn with older varieties without these features.