What to look for
- From-date GDD tracking, not only seasonal GDD.
- Grass-type-appropriate base temperature: base 32°F for cool-season grasses (Cornell research context); base 50°F for warm-season grasses like bermuda (Reasor et al. 2018, Crop Science).
- Application log with rate, turf condition, and mowing response.
- Clear warnings that labels and turf stress still matter.
Why GDD beats calendar days
Cornell Turfgrass Program explains that warmer temperatures shorten the suppression phase because turf breaks down PGRs faster. That makes fixed calendar intervals less consistent across spring, summer, and fall.