How the grass seed calculator works
Seed is sold by coverage rate
Extension services publish seeding rates per 1,000 sq ft, and they differ hugely by species:Kentucky bluegrass is a fine, aggressive spreader (2–3 lb/1,000), while tall fescue is a bunch-grass that needs each plant's space seeded (6–8 lb/1,000). Warm-season lawns (bermuda, zoysia) need far less by weight (1–2 lb/1,000) because their seeds are small and they spread.
New lawn vs overseeding
Overseeding uses about half the new-lawn rate — you're thickening an existing stand, not establishing bare soil. Seeding heavier than the rate wastes money and creates disease-prone congestion; seeding lighter leaves gaps for weeds. If your spreader forces a choice, slightly heavy on overseeding beats slightly light.
Timing beats everything else
- Cool-season lawns (bluegrass, fescues, rye): late summer to early fall is prime — warm soil, cool air, fewer weeds. Spring is the second choice.
- Warm-season lawns (bermuda, zoysia): late spring, after soil truly warms.
After seeding: keep the top inch of soil consistently moist with light daily watering until germination, then taper to deeper, less frequent watering. Most seeding failures are watering failures, not seed failures.