Best soil temperature app for pre-emergent

• Current soil temperature and trend.
• Pre-emergent guidance tied to crabgrass germination thresholds.
• Grass-specific notes for Bermuda, zoysia, St. Augustine, and cool-season lawns.
• A treatment log so you know what was applied and watered in.

University of Minnesota Extension says pre-emergent herbicides should be applied before soil temperatures have reached approximately 55°F, while Penn State notes crabgrass germination when temperatures in the upper inch of soil reach approximately 55 to 58°F at daybreak for 4 to 5 days.