Crabgrass Is Already Showing Up—Here’s How to Stop It

If you’ve haven’t‘ made your spring preemergent application yet, you may have already noticed the dreaded crabgrass showing up in your yard. Don’t blame yourself. A late warm spell has caused weeds, along with insects, to awaken earlier than normal. In fact, for some areas the window for applying a preemergent is rapidly closing. 

Related: Overseeding? Here’s How to Keep Weeds Out

Why Crabgrass is Arriving Early This Year

Crabgrass’s early entrance to your lawn this spring has to do with two major factors. First, it’s been a warmer than average late winter. In fact, the U.S. 's fourth warmest February on record dating back through 132 years of meteorological data, according to National Oceanic and Atmospheric Administration (NOAA), with above average temperatures particularly in the West and South. That, coupled with heavy snowfall that has kept soil moist has created a recipe for rapid weed germination and growth. 

CrabGrass Timing Window

Crabgrass germinates when soil temperatures reach 55 degrees Fahrenheit. Given those warmer temperatures, many areas are experiencing those temperatures earlier than normal. That’s throwing off people’s calendars, causing them to miss that crucial preemergent application window. Once crabgrass germinates, preemergents are powerless to stop it. By the time it’s safe to apply post emergents to your lawn, that crabgrass will already have established itself, making it a season long battle to get rid of it. 

How to Tell if You’ve Missed the Preemergent Window

If you’re not sure if that preemergent window is still open for your lawn, there are a few ways to check:

• Visible weeds: If you’re already seeing crabgrass and other weeds sprouting throughout your yard, you’ve likely missed the window for putting down preemergent. 
• Warm soil temps: One easy way to see where your lawn is at is to take a quick temperature reading using a soil thermometer or even a kitchen meat thermometer. Push the probe about four inches deep into the soil and let it sit for a few minutes. If the temperature is above 55 degrees, weeds are germinating. 
• Survey Your Neighborhood: Take a walk around your neighborhood and make a quick assessment of your neighbor's lawns. If you see weeds popping up around your neighborhood, it’s a clear sign that conditions are right for weed seed germination. 

Related: Here's How I Spring Seed My Lawn as a Yardcare Expert

What to Do If You’re Still in the Window

If your soil temperatures are still hovering under 55°F and you’re not seeing significant weed growth in your lawn or your neighbor's lawns, then there is still time. Apply preemergent right away to keep crabgrass at bay. Even if you do spot some weeds, applying preemergent can still be effective as it will stop seed that hasn’t yet sprouted from germinating. 

What to Do if You Missed the Window

• Spot treat: Take out that early crabgrass by spraying them directly with a selective herbicide using a handheld sprayer. 
• Post emergent: Once your lawn is actively growing and you’ve mowed it a few times, hit with a post emergent treatment to take out existing crabgrass. 

Mow high: Allow your grass to grow a little taller than normal, which will allow it to crowd out crabgrass.