What Month Should You Apply Pre-Emergent Herbicides

This page is a general DIY guide that explains when to apply pre-emergent herbicides for cool-seasoned and warm-seasoned grass. Using the information and methods suggested throughout this article will help to prevent weeds in your lawn. Follow this guide and use the recommended products and methods and we guarantee a greener, and thicker lawn.

Rather than waiting for weeds to appear in your yard, think about prevention. This can be done by applying a pre-emergent herbicide before weeds appear. The end goal is to suppress or prevent the weed before it begins to grow and put out shoots so desired plants do not have to compete for nutrients, space, water, and sunlight.

So the true question every gardener or homeowner wants to know is when to apply pre-emergent herbicide? While it may sound simple, an early or late application of pre-emergent herbicides can cause little control over weeds, drift of product onto undesired areas, and waste of product materials. Learn when to apply a pre-emergent herbicide to your lawn as well as how it works with the information in this DIY guide.

How Pre-Emergent Herbicides Work

When a pre-emergent herbicide is applied to your turf then properly watered in, the chemical moves down through the turf to make contact with the soil. The herbicide then chemically binds itself to the upper soil surface where most weeds germinate. As the weed seeds germinate and spread its roots it will come into contact with the treated soil, which inhibits the growth of shoots and roots eventually leading to death of weed before it emerges in turf.

When to Apply Pre-Emergent Herbicides

A pre-emergent herbicide can be applied throughout the year, but the best results for weed control is in the early spring and early fall. Both of these seasons are active periods for germinating weeds. Contrary to belief, applications of pre-emergent herbicides in the spring will control weeds in the summer and fall whereas applications in the fall will control weeds in the spring.

Spring pre-emergent herbicides can be applied when your soil has warmed from winter and when the soil temperatures have been consistently 55 degrees Fahrenheit. Depending on your geographical location this could be the beginning of February to March.

A fall pre-emergent herbicide application can be made from September to November and when soil temperatures are below 70 degrees Fahrenheit.

If you missed the window of opportunity for an pre-emergent application, then you can apply a post-emergent herbicide for present weeds.

How to Apply Pre-Emergent Herbicides

Step 1: Determine Turf Type and Check Product Label

Not all pre-emergent herbicides can be used on certain types of turf and may have restrictions on when to apply them. We recommend using a granular pre-emergent herbicide like Barricade Granular Pre-Emergent Herbicide as it requires no mixing and provides a wide range of control against weeds on different grass types.

Step 2: Apply Pre-Emergent Herbicide

Determine how much Barricade Granular Pre-Emergent Herbicide to use by measuring the square footage of the treatment area. To do this, measure the treatment areas length and width in feet then multiply them together (length X width = square footage).

Depending on your turf species, you may be using anywhere from 1.5 to 4 lbs. of Barricade Granular Pre-Emergent Herbicide per 1,000 sq. ft.

Load the proper amount of Barricade Granular Pre-Emergent Herbicide into your calibrated spreader. Then, perform 2 perpendicular passes to get uniform coverage. If any granules land on your driveway, sidewalk, or street, sweep the product back onto your lawn. Activate the granules by watering your lawn with at least 0.5 inches of water for best results.

When done properly, you will see little no weed activity as the season progresses. Keep in mind that cultural practices like core aeration may weaken control.

Key Takeaways

Should Pre-Emergent Be Applied Twice

• Yes, a pre-emergent herbicide needs to be applied in the spring and fall for total weed control.

Does Pre-Emergent Work on Existing Weeds

• A pre-emergent herbicide will have no effect on existing weeds in your lawn.

Can You Apply A Pre-Emergent Too Early?

• If a pre-emergent is applied to early then it can be washed or blown away from the weather or its rate of control could be lessened by the time weeds germinate.