A well-manicured lawn can be achieved using a preemergence herbicide to prevent annual weed seeds from germinating.
Samantha M. Brown, © 2021, Clemson Extension
Preemergence herbicides (often called pre-emergent or preemergent herbicides) are considered a proactive approach when keeping weeds at bay. Deciding when to apply the product can be difficult with the false springs we often experience in South Carolina.
How Preemergence Herbicides Work
- Preemergence herbicides create a thin chemical barrier within the first few inches of the topsoil to help prevent most annual weeds from emerging.
- Help control most annual weeds when applied before weed seeds germinate in spring and fall.
When to Apply
- Apply before weed seeds germinate.
- Four consecutive days of 65 to 70° F weather will allow the soil temperature to rise for possible weed seed germination.
Activation and Effectiveness
- Most preemergence herbicides need at least 1/4 inch of water after application to activate the chemical.
- Preemergence herbicides can last in the soil for 6 to 12 weeks.
- A second application may be needed closer to summer to control pesky weeds such as crabgrass.
For more information, see HGIC 2310 Managing Weeds in Warm Season Lawns.
