Best GDD tracker for Primo Maxx

• From-date GDD tracking, not only seasonal GDD.
• Research-aligned Celsius-scale PGR math: cool-season trinexapac sessions use a 0°C base, while warm-season trinexapac sessions use a 10°C base. Displayed Fahrenheit highs and lows should be converted internally before GDD is calculated.
• Application log with rate, turf condition, and mowing response.
• Clear warnings that labels and turf stress still matter.

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. Use the free GDD calculator to calculate from your last spray date.