You can’t determine soil temperatures by looking at a calendar. While this seems like a simple enough concept, there are still numerous ill-timed applications made based on the date and not specific environmental conditions. Relying solely upon the calendar for application timing will yield inconsistent results and is particularly problematic for preemergence herbicide treatments. When temperatures warm earlier than normal, which is the case for much of the country this year, a number of weeds can become established early and late preemergence herbicides will be less effective.

Crabgrass seed typically begins to germinate when soil temperatures reach 55 degrees Fahrenheit for three or more days. For those in the southernmost part of the U.S., this threshold has already been met and it won’t be much longer for those in the transition zone to reach that soil temperature level. If you haven’t been keeping a close eye on soil temperatures this year, now is the time.

Measuring soil temperatures is a very simple process that can be accomplished with an inexpensive thermometer. If you don’t have a thermometer handy, there are numerous online resources that provide soil temperatures in your area. Most are completely free to use and some even provide historical data so you can see how temperatures and growth might differ from previous years.

Proper timing is imperative when it comes to preemergence herbicide treatments so make sure to get your product down before things get too warm. Don’t fall victim to a late treatment and disappointing weed control.