PatchFree tool
Growing Degree Days (GDD) calculator
Accumulated GDD base 50°F from January 1 at your ZIP. Use it for pre-emergent windows, PGR reapplication timing, and warm-season green-up cues.
GDD reference (base 50°F)
- 0–50 GDD — apply crabgrass pre-emergent.
- 50–150 GDD — crabgrass germination window; pre-emergent still effective early.
- 150+ GDD — post-emergent for visible crabgrass.
- ~200–350 GDD — Primo Maxx (trinexapac-ethyl) typical reapplication interval on warm-season turf.
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Patch times every application to your GDD, soil temperature, and grass type — and diagnoses problems from a photo.
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