As of March 12, Is is too late to apply pre-emergent crabgrass killer to my lawn? The rule of thumb I have heard over the years from local Turf Specialists is to apply it no later than St. Patrick's Day. However, since spring this year is about 3 weeks early, have I waited too late to apply? I usually apply fertilizer with the pre-emergent crabgrass killer in mid March. Thanks, Tom
Charles County Maryland
St. Patrick's Day is a new one for us. It is generally way too early to apply crabgrass pre-emergent.
You are right that the weather varies a great deal from year to year. That's why a particular date doesn't work well. However, plants do adjust their bloom time somewhat to the weather. So, the rule of thumb for timing is to apply it when forsythia blooms are fading and falling.
If you have stiltgrass problems, then apply about a week earlier.
Here is our webpage on crabgrass, which includes timing tips: https://extension.umd.edu/hgic/topics/crabgrass