SeedCast
16-day overseeding forecast for UK lawns
Overseeding works best when soil and air temperatures encourage germination without frost risk or heat stress.
- Night temperature ≥ 8°C — warm enough for seed germination
- Day temperature 10°C – 25°C — active grass-growing range
- Rainfall 1 mm – 15 mm per day — keeps soil moist without waterlogging
- Frost risk (below 2°C) — automatic fail; kills germinating seed
- Heavy rain (above 20 mm) — waterlogging prevents germination
A seeding window is 5 or more consecutive days where every day scores above 50 out of 100. The app searches the full 16-day forecast to find all windows and tells you whether now is ideal or when to wait.
Weather data: Open-Meteo (free, no API key required). Postcode lookup: postcodes.io.
Checking 16-day forecast…