If you do any research online about the timing of the fall pre-emergent, you will likely find a handful of hard dates. The most common one we hear about is Labor Day…”you HAVE to have your pre-emergent put down by Labor Day!”
The reality is that whether its the spring or fall pre-emergent, the timing is all about the weather and not a specific date. Soil temperatures are what you are up against, and soil temperatures fluctuate with the weather (for the fall pre-emergent, you want to apply before the soil temperatures reach 70 degrees).
These hard dates that you find online are typically based on historical weather data, which is a great starting point to work with, but weather patterns are simply not consistent from year to year. What may have been the perfect timing for pre-emergent last year will not likely be the same for this year.
To be clear, I am NOT saying that sticking to these deadlines is a bad thing. If you were working with a deadline and you got your pre-emergent down within that deadline, then you did good!
The danger is when people miss the deadline and skip the application altogether because they assume it is a lost cause at that point. That is a HUGE MISTAKE! These applications will continue to be very effective well after any deadline you read about online.
If you apply your pre-emergent too early, you will likely see some coverage early on but will deal with weed breakthrough later in the season. On the flip side, apply your pre-emergent too late and you will have breakthrough early on, but good coverage later in the season. Either way, you are still going to see a benefit from your pre-emergent application.
Bottom line…don’t let a hard date deadline that you found online scare you away from applying your pre-emergent right now. Its still warm, soil temperatures are in the low 70s, there is still time! Get your pre-emergent down ASAP!
