Grass Seed Calculator

Overseeding at the full new-lawn rate packs seedlings so tightly they compete with each other and with established turf. That dense competition increases damping-off disease and rarely produces a thicker lawn than half the rate. If you are slit-seeding distinct bare patches, treat those patches as new seeding at the full rate.

Late summer to early fall (August to October in most of the US) is the best time for cool-season grasses - tall fescue, Kentucky bluegrass, perennial ryegrass. The soil is warm for quick germination, air temperatures favor seedling growth, and fall weeds are less aggressive than summer ones. Early spring is the runner-up but you will fight summer weeds and heat.

Yes. Cheap seed mixes often have lower purity (more inert material) and lower germination percentages. If the label shows 75% germination instead of 90%, you need to seed about 20% heavier to achieve the same stand. Always read the seed tag - it is required by law to show purity and germination.

Almost always inconsistent moisture or poor seed-to-soil contact. Lightly rake or roll after sowing and never let the surface dry out. Aim for light, frequent watering (two to three times daily) until germination, then taper to deeper, less frequent irrigation to drive roots down.