If you want a lush, weed-free lawn this year, one of the most important steps you can take is applying a pre-emergent herbicide to prevent crabgrass from taking over. For homeowners and property managers with cool-season lawns—like fescue, Kentucky bluegrass, and perennial ryegrass—timing and product choice are key to effective crabgrass prevention.

What Is Crabgrass and Why Is It a Problem?

Crabgrass is an aggressive annual weed that thrives in thinning turf and bare soil patches. It germinates in the spring, grows rapidly throughout the summer, and drops thousands of seeds before dying in the fall. These seeds then overwinter in your soil, waiting to sprout when temperatures rise again. If left unchecked, crabgrass can quickly choke out desirable turfgrass, leaving your lawn patchy and weak.

How Pre-Emergent Herbicides Work

Pre-emergent herbicides work by creating a chemical barrier in the soil that prevents crabgrass seeds from sprouting. However, they do not kill existing weeds, so they must be applied before germination occurs. The key to success is getting the timing right and ensuring even coverage across your lawn.

When to Apply Pre-Emergent for Crabgrass in Cool-Season Lawns

The ideal time to apply a pre-emergent for crabgrass control in cool-season lawns is when soil temperatures consistently reach 50–55°F for several days. This typically happens in early to mid-spring, depending on your location. A good rule of thumb is to apply pre-emergent when forsythia bushes start blooming, as this is a natural indicator of soil temperature.

Best Pre-Emergent Herbicides for Crabgrass

When choosing a pre-emergent, look for products containing prodiamine, dithiopyr, or pendimethalin, as these are highly effective against crabgrass. Here are some recommended options:

• Prodiamine (Barricade) – Long-lasting control, ideal for early applications.

  
  

• Dithiopyr (Dimension) – Provides both pre- and early post-emergent control.

  
  

• Pendimethalin (Scotts Halts) – Readily available and effective but breaks down faster than other options.

  
  
  
  

Application Tips for Maximum Effectiveness

To get the best results from your pre-emergent application:

1. Apply at the right time – Use a soil thermometer or local weather resources to track soil temperatures.

   
   

2. Use a spreader for even coverage – Uneven application can leave gaps where crabgrass can still

   germinate.

   
   

3. Water it in – Most pre-emergent herbicides need to be watered in within a few days to activate the barrier.

   
   

4. Avoid aerating after application – Core aeration can disrupt the herbicide barrier and reduce its effectiveness.

   
   
   
   

What If You Miss the Pre-Emergent Window?

If crabgrass has already started sprouting, post-emergent herbicides like quinclorac can help control young plants. However, prevention is always more effective than treatment.

Conclusion

Applying pre-emergent herbicide at the right time is one of the best ways to keep your cool-season lawn free of crabgrass. By monitoring soil temperatures, choosing the right product, and ensuring even application, you can enjoy a thick, healthy lawn all season long. If you need professional help with crabgrass prevention and lawn care, reach out to us today!