Hello Harvey,

Now is the ideal time to apply crabgrass pre-emergent herbicide in Ottawa County. Pre-emergent herbicide should be applied when soil temperature is between 50 and 55 degrees F. The best natural indication that the soil is at the correct temperature is the bloom of the forsythia shrub.

MSU also maintains a Growing Degree Day tracker that monitors daily temperatures at various locations and estimates the overall cumulative “warming” for the season. This Degree Days measure can be used to predict certain natural phenomena. One that is tracked is the temperature for pre-emergent herbicide application. The GDD Tracker can be found at https://gddtracker.msu.edu/

Enter your zip code and choose “Crabgrass PRE” in the right panel. The green band shows where it is optimal to apply crabgrass pre-emergent.

Another excellent reference can be found at https://www.canr.msu.edu/news/timing_crabgrass_pre_emergence_applications

Remember whenever using any fertilizer or herbicide product, read and follow the label directions. And avoid applying where runoff can enter the watershed system.