What Is Pre-Emergent Weed Killer?

Key Takeaways

Pre-emergent strategies offer:
  • Effective Prevention: Pre-emergent herbicides form a barrier that stops weeds before they grow, offering a proactive approach to lawn maintenance.
  • Strategic Application: Timing is critical with pre-emergent herbicides, requiring application in early spring or fall for optimal effectiveness.
  • Expert Care: Professional lawn services tailor treatments to local conditions, enhancing weed control while preserving desirable plants.
  • Variety for Needs: These herbicides are available in both granular and liquid forms, including organic options for those seeking minimal environmental impact.
Check out our pre-emergent weed control services.

Pre-Emergent weed killers are designed to kill weeds before they emerge. This type of weed killer is especially beneficial in areas where vegetation is dense and close together, as it allows the herbicide to reach all the weeds.

If you know your lawn is prone to pesky weeds in the spring and summer, try using a pre-emergent weed control treatment to help stop them before they emerge. These treatments will help keep your lawn looking healthy and weed-free all season long!

What Do Pre-Emergent Weed Killers Do?

Pre-emergent herbicides keep weeds out of the top inch or two of soil, preventing them from growing above ground. This barrier protects the soil and keeps it healthy and weed-free.

Pre-emergent herbicides are applied before the weeds emerge, usually in the spring and fall, times of the year when weeds begin to germinate.

Preventing young weed seeds from emerging is key to limiting the root system development of that weed. By pre-emergently killing the plants before they have a chance to grow, herbicides prevent them from establishing and reproducing.

Pre-emergent herbicides can harm plants and flowers, so avoiding using them near vegetation is best.

What Are Post-Emergent Herbicides?

Post-emergent herbicides control existing weeds in the lawn, including dandelions, clover, and other broadleaf weeds. These herbicides are applied to actively growing weeds after they have emerged from the soil. 

Post-emergent herbicides are ineffective against grassy weeds such as crabgrass, but they can be used to control other weeds that have already taken hold in the lawn. As with pre-emergent herbicides, always read and follow the directions on the label when using post-emergent herbicides.

When To Apply Pre-Emergent Weed Killer

Two crucial factors determine the right time to apply herbicides: the season and the ground temperature.

To get ahead of early spring and summer weeds, apply pre-emergent herbicides around mid-March to help control these problematic plants. To ensure you're applying them at the right time, pay attention to ground temperature too! If the ground temperature is above 55 degrees for at least 48 hours, it's an excellent time to use a pre-emergent herbicide.

To measure the ground temperature, you can stick a thermometer 2 inches below the soil. This will help you to determine whether the ground is too cold or too hot.

After applying the pre-emergent herbicide, be sure to water it well. This will help ensure that the herbicide is activated and has worked its way down into the soil where it can be effective.

Once the pre-emergent herbicides have been applied, keeping an eye out for any new weeds that may sprout up is essential. If you spot any weeds emerging, take care of them promptly. You can pull them out by hand or use a post-emergent herbicide to treat them.

If you are doing a fall application, apply the pre-emergent herbicide when ground temperatures reach 70 degrees and continue to drop. This will help prevent winter weeds from growing!

Pre-emergent herbicides effectively suppress weed growth before germinating, but they will have little effect if applied after the weeds have already sprouted.

It's important to water your lawn regularly and mow it at least once a week to keep weeds from taking over. Finally, enrich the soil with fertilizer and compost to help your grass and plants grow strong and healthy. 

Call In The Professionals

If you live in the Reno/Sparks area, call Cory’s Lawn Service, providing high-quality fertilization and weed control programs. With years of lawn care experience, numerous horticulture degrees, and licensed spray technicians, we can help your turf get what it needs to be weed-free and lush green.

We are focused on delivering top-notch customer service, maintaining beautiful lawns, and giving our customers more time to spend on what is most important.