Plants don’t grow based on the calendar. Instead, they react to temperature. And while on average, optimum timing for pre-emergent herbicide application may be April 16th, we all know that there is no such thing as an average year when it comes to weather.

Growing degree days are a simple way to adjust your practices based on the current weather. Use the following growing degree day maps and models to maximize your efficiency.

Special thanks to Rick Wayne and Bill Bland of the UW-Madison Soil Science Department for creating and maintaining these maps for us.

Annual bluegrass seed head suppression with Proxy/Primo

Annual bluegrass seed head suppression with Embark

Annual bluegrass seed head flush

Crabgrass pre-emergent herbicide timer

Spring broadleaf herbicide timer

Japanese beetle grub preventative timer

Plant growth regulator re-application intervals