Bermuda grass GDD green-up guide

University extension sources do not establish confirmed GDD greenup thresholds for bermuda grass. Texas A&M AgriLife Extension identifies 65°F soil temperature at depth, with consistent nighttime temperatures above 60°F, as the signal for active bermuda growth and recovery. The 50-55°F soil temperature window is the established pre-emergent crabgrass timing trigger (University of Minnesota Extension; Penn State Extension), not a bermuda greenup signal.

Where GDD is useful: comparing this spring's heat accumulation to last spring's at your own location. Build your own multi-season baseline by pairing GDD totals with the date you first saw green shoots each year.

GDD models help compare spring heat accumulation, but Bermuda green-up is also affected by cultivar, shade, mowing height, winter injury, soil moisture, and local microclimate. Use GDD with visual green-up and soil temperature rather than as a single automatic trigger.

• Comparing this spring to last spring in the same location.
• Pairing heat accumulation with soil-temperature pre-emergent timing.
• Tracking PGR intervals separately from seasonal turf GDD.

The GDD Calculator shows seasonal turf GDD from January 1 and a separate from-date calculation for PGR timing. The app lets you log what you applied and compare the results later.