When to Apply Pre-Emergent in Louisiana
The best time to apply pre-emergent in Louisiana is late january to late february. Use the GDD tracker below for precise timing based on your ZIP code.
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Pre-Emergent Timing in Louisiana
Spring Application
Late January to late February
Target: when soil temperature reaches 55°F at 4-inch depth for several consecutive days
Fall Application
Late August to mid-September
Prevents winter annual weeds like annual bluegrass (Poa annua)
Common Grass Types in Louisiana
Louisiana has a warm-season climate, meaning soil temperatures rise early in the year. Crabgrass and other summer annual weeds can begin germinating as early as late winter, so early pre-emergent application is critical.
Pre-Emergent Tips for Louisiana
- Southern Louisiana (New Orleans, Baton Rouge) should apply by mid-February.
- Northern Louisiana (Shreveport, Monroe) can wait until late February to early March.
- Louisiana's warm, humid climate creates aggressive crabgrass and goosegrass pressure.
- A fall application is strongly recommended for winter annual weed prevention.
- LSU AgCenter recommends atrazine for centipede and St. Augustine lawns.
Local Expert Resources
For research-backed lawn care advice specific to Louisiana, visit your state's university extension service:
LSU AgCenterFrequently Asked Questions
When should I apply pre-emergent in Louisiana?
In Louisiana, the best time to apply pre-emergent is late january to late february. Use Growing Degree Days (GDD) tracking for precise timing based on your local soil temperature.
What grass types are common in Louisiana?
Common grass types in Louisiana include St. Augustine Grass, Bermuda Grass, Centipede Grass, Zoysia Grass. Louisiana is in USDA Hardiness Zones 8a-9b.
What is the best pre-emergent herbicide for Louisiana?
For most lawns in Louisiana, Prodiamine (Prodiamine 65 WDG) provides the longest-lasting barrier at 8+ months. If you are applying late, Dithiopyr (Dimension 2EW) is a better choice because it offers early post-emergent control on young crabgrass. Compare all pre-emergent options.
What soil temperature triggers pre-emergent application in Louisiana?
Apply pre-emergent when soil temperature at 4-inch depth reaches 55°F for several consecutive days. In Louisiana, this typically corresponds to 150–200 Growing Degree Days (base 50°F) accumulated from January 1.
Should I apply pre-emergent in the fall in Louisiana?
Yes. In Louisiana, a fall pre-emergent application (late august to mid-september) prevents winter annual weeds like Poa annua (annual bluegrass) and henbit from establishing.
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Don't guess -- use Growing Degree Days to know exactly when to apply pre-emergent herbicide at your location.
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