The best times to overseed a lawn generally fall into two main periods:
- Spring: from March to early May
- Late summer to early autumn: from late August through September
Autumn is often considered the best time to overseed because cooler temperatures and shorter nights favor seed germination and grass growth. Avoid overseeding in hot summer weather to prevent wasting seed and resources due to poor germination in high heat. More specifically, if you have cool-season grasses (common in northern areas), overseed in fall or spring, with fall preferred. Soil temperatures should ideally be between 50°F and 65°F (10°C to 18°C) for best germination. For warm-season grasses (common in southern areas), overseed in late spring or early summer when soil temperatures are between 70°F and 90°F (21°C to 32°C). Fall overseeding should occur ideally about 45 days before the first expected frost. Proper preparation like mowing shorter, aerating, raking thatch, and consistent watering improves the success of overseeding. In summary, aim for:
- Early spring (March to May)
- Late summer to early fall (late August to September)
Avoid high heat and extreme cold periods for overseeding success.
