Pre-Emergent Herbicide – Understanding When to Apply

As a landscape contractor, one of the most important steps in guaranteeing a healthy and attractive lawn for your clients is to prevent the growth of undesirable grasses before they can become a problem. Applying pre-emergent herbicides is an effective way to proactively eliminate them early on. Pre-emergent contains chemicals that work to inhibit the germination and growth of crabgrass seeds, preventing them from taking root in the lawn. But when it comes to applying pre-emergent, timing is crucial and there are several factors that need to be considered to ensure an effective application.

Soil Temperature

When it comes to timing your pre-emergent applications, soil temperature sits near the top of factors that must be considered. Because they inhibit the germination of crabgrass seeds, pre-emergent herbicides should be applied before soil temperatures reach a consistent 50-55° F for 7-10 days. Crabgrass, which is one of the most common lawn weeds, tends to germinate around the first week of May, but this can vary depending on location. To ensure the correct timing of application, landscape contractors should investigate the specifics of their area. Michigan State University’s GDD Tracker has a Crabgrass/Annual Bluegrass Pre-emergence Timer that shows the optimal times to complete your application.


Rainfall is another important factor to keep in mind when applying pre-emergent herbicides. Following application, your pre-emergent herbicide needs to be watered-in for it to be activated. If there is no rainfall or irrigation system in place, the timing of your application may need to be adjusted accordingly. It is also important not to apply the herbicide right before a massive rainfall or storm, as the aggressive weather could potentially wash away your herbicides before they are able to be watered-in.

Application Methods (Granular vs Liquid)

When it comes to deciding how you want to apply your pre-emergent herbicides, deciding whether to use a granular and liquid product is important. While both are affective at inhibiting the germination of crabgrass, there are some key differences to pay attention to.

Granular pre-emergent herbicides, like Barricade or Dimension, are added to a carrier such as fertilizer or lime, and are applied using a spreader. They are often used in lawns and gardens due to the simplicity of their applications. When compared to their liquid counterparts, granular herbicides tend to be easier to handle and store. Following your application, it is important to water-in granular herbicides so that you guarantee that they are being taken up by the soil.

Liquid pre-emergent herbicides, such as Dimension 2EW Pre-Emergent Herbicide or Barricade 65WG Pre-Emergent Herbicide, are applied in liquid form using a sprayer. They are more concentrated than granular herbicides and can be more effective in controlling weeds due to their 100% coverage. Liquid herbicides are also easier to mix and apply, making them more convenient for spot treatments. For larger plots of land, commercial-grade sprayers may be used to guarantee an effective application.

Other Lawn Care Plans

One thing to keep in mind is that you should never apply pre-emergent herbicides if you are planning on seeding in the spring. If a pre-emergent is applied, your new grass seed will be prevented from germinating, which virtually cancels out all the work you have done on both fronts. Similarly, if you are planning on aerating or over-seeding, pre-emergent herbicides should not be used. In cases like these, it may be better to use post-emergent control solutions, such as BASF’s Drive XLR8 Post-Emergent Herbicide, to manage any existing crabgrass. However, it is important to note that post-emergent herbicides can also be damaging to desirable grasses if not applied correctly, so it is crucial to read and follow the product labels carefully. Just like with pre-emergent herbicides, post-emergent herbicides rely on proper timing to ensure their success. They should be applied while the crabgrass is actively growing, rather than waiting for the plant to fully mature.

Overall, pre-emergent herbicides are an essential tool for preventing crabgrass growth. Understanding the key factors for pre-emergent herbicide applications, and which products are best for you, will yield stronger results and shut down crabgrass problems before they can even arise. If you plan your application for when the soil is at an optimal temperature and precipitation is right, and account for your other lawn care plans, you will certainly be rewarded with a healthy lawn free of any undesirable grasses.

If you have any further questions or would like to learn more about our wide selection of pre-emergent herbicides, contact your Reinders rep today!

Check Out Some of Our Top Pre-Emergent Herbicide Products

Barricade® 65WG herbicide is a water-dispersible granule that provides the ease of handling and reduced packaging of a dry formulation. Adjust the rate to provide the desired length of control. Even at its lowest rate (0.5 lbs. /A) Barricade can provide up to three months of effective crabgrass control. 

By providing both pre- and early post-emergence control, Dimension offers a longer application window than other pre-emergence herbicides which affords more time to make applications. Confidently use Dimension from early to mid-season without having to worry about switching products after crabgrass has germinated. 

Check out our Turf & Landscaping library to read more help you further plan for the spring season!

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