How To Apply Pre-Emergent Herbicide For The Best Results

Timing is everything when it comes to effectively using pre-emergent herbicides to prevent weeds in your lawn. It’s essential to apply the herbicide before the weeds germinate. However, applying it too early could impact its effectiveness in addressing the issue. And if you wait too long, it won’t be quite right either.

With all of these factors to consider, you’ll want to make sure you’re getting the best value out of your herbicide-killer of choice. 

In this blog post, we’ll walk you through the dos and don’ts of adequately applying a pre-emergent herbicide.

When Should You Apply Pre-Emergent for Fall or Winter Weeds?

When it comes to taking the best approach for weed treatment, consulting with your local Sod Depot professional is always guaranteed to lead to success. But for those who prefer to get their hands dirty, you need to know when to apply any pre-emergent. When treating seasonal weeds, you’ll want to apply the season before ensuring that the treatment kills the weeds before they’ve had the chance to germinate.

In addition to choosing the right season to apply your pre-emergent, you’ll also need to check the temperature of your soil to make sure it’s ready to be treated. The best temperature to apply pre-emergent for summer weeds is when the ground has been at least 55 degrees for 48 hours or longer. For winter weeds, you’re looking for a ground temperature that is at least 70 degrees and continues to drop from there. Sticking a thermometer two inches below your soil is a great way to measure the temperature. 

What Month Do You Put Down Pre-Emergent?

The whole purpose of a pre-emergent is to prevent weeds from sprouting each season. Because pre-emergents are typically effective for 3-5 months, you’ll want to keep that in mind when treating certain types of weeds. For winter and fall weeds, like hairy bittercress or prickly lettuce, the best time to apply pre-emergent herbicide is from August until November. 

Does Pre-Emergent Need to be Watered In?

Almost every pre-emergent herbicide needs water to work its magic. Watering your soil 3-5 days after your pre-emergent has been applied helps it move through the soil to reach seeds getting ready to germinate. While you want to water your lawn during the ideal time period after pre-emergent application, your lawn or soil should be dry when you treat the area. 

Can You Mow Before Pre-Emergent?

Pre-emergent herbicides differ from post-emergent herbicide treatments in that they can be applied right after mowing. Because this particular herbicide targets weeds before germination, mowing doesn’t impact its ability to kill them.


As you can see, there are several things you need to consider before applying pre-emergent herbicide to your lawn. If you still need help or guidance, feel free to reach out to us at Sod Depot. We’ll be happy to help!