When to Apply Crabgrass Preemergent in Georgia

Quick Answer: Georgia homeowners should apply crabgrass preemergent herbicides in late February to early March, when soil temperatures consistently reach 50-55°F. This timing aligns with Georgia's USDA zones 7a-9a and prevents crabgrass germination in Bermudagrass, Zoysiagrass, Centipedegrass, and St. Augustinegrass lawns.

Key Takeaways

• Apply preemergent between late February and early March in Georgia
• Monitor soil temperature at 2-inch depth reaching 50-55°F consistently
• Northern Georgia (zone 7a) may need applications closer to mid-March
• Southern Georgia (zones 8b-9a) should target late February timing
• Second application may be needed 8-10 weeks after the first for season-long control

Georgia's humid subtropical climate creates ideal conditions for crabgrass to thrive in warm-season lawns. With high humidity, 50 inches of annual rainfall, and hot summers averaging 90°F, timing your preemergent application correctly is crucial for protecting your Bermudagrass, Zoysiagrass, Centipedegrass, or St. Augustinegrass from this persistent weed[1].

What Is the Best Timing for Preemergent in Georgia?

The optimal timing for crabgrass preemergent in Georgia depends on soil temperature rather than calendar dates. Crabgrass seeds germinate when soil temperatures reach 55-60°F for several consecutive days[2]. To prevent germination, you must apply preemergent herbicides before this temperature threshold.

In Georgia's diverse climate zones, this typically occurs:

• Northern Georgia (Zone 7a): Mid-March to early April
• Central Georgia (Zones 7b-8a): Early to mid-March
• Southern Georgia (Zones 8b-9a): Late February to early March

Use a soil thermometer to measure temperature at 2-inch depth in multiple lawn areas. When readings consistently show 50-55°F, it's time to apply your preemergent[3]. The UGA Cooperative Extension recommends this soil temperature method over calendar-based timing for Georgia's varying microclimates[1].

How Do You Apply Preemergent on Georgia Grass Types?

Georgia's primary warm-season grasses each have specific considerations for preemergent applications:

Bermudagrass: The most tolerant grass for preemergent herbicides. Apply when Bermuda begins breaking dormancy but before active growth starts. Most preemergent products are safe for established Bermudagrass[4].

Zoysiagrass: Similar tolerance to Bermudagrass but emerges from dormancy later. Time applications for late February in south Georgia, early March in central areas, and mid-March in northern zones.

Centipedegrass: More sensitive to herbicides than Bermuda or Zoysia. Use lower application rates and avoid products containing atrazine, which can damage Centipedegrass[1].

St. Augustinegrass: Moderate herbicide tolerance. Avoid preemergents containing simazine, which can cause yellowing in St. Augustine varieties common in coastal Georgia[5].

Tall Fescue (North Georgia): For cool-season areas in north Georgia mountains, apply preemergent in early spring when forsythia blooms, typically late February to early March.

Always water in preemergent herbicides within 7 days of application. Georgia's high humidity and frequent spring rains usually provide adequate moisture, but irrigation may be needed during dry periods[2].

Should You Make a Second Preemergent Application?

Georgia's long growing season often requires two preemergent applications for complete crabgrass control. Most preemergent herbicides provide 8-12 weeks of protection, but crabgrass can germinate from March through June in Georgia's warm climate[6].

Plan your second application:

• 8-10 weeks after the first application
• Before soil temperatures reach 70°F consistently
• Typically late May to early June

This second application is especially important in southern Georgia zones 8b-9a, where the extended warm season allows multiple crabgrass germination periods. Northern Georgia homeowners in zone 7a may achieve adequate control with a single, properly timed application[1].

Consider your lawn's history with crabgrass problems. Lawns with severe previous infestations benefit from the two-application approach, while well-maintained lawns with minimal weed pressure may need only one treatment.

What Products Work Best in Georgia's Climate?

Choose preemergent herbicides suited to Georgia's humid conditions and grass types. Granular formulations work well in Georgia's climate because they're less affected by the state's frequent spring rains compared to liquid applications[3].

Effective active ingredients for Georgia include:

• Prodiamine: Long-lasting control, safe for most warm-season grasses
• Dithiopyr: Dual pre and early post-emergent activity
• Pendimethalin: Economical option with good crabgrass control
• Isoxaben: Excellent for broadleaf weed prevention alongside crabgrass control

Apply when rain isn't forecast for 24 hours to allow proper absorption. With Georgia's average 50 inches of annual rainfall, timing around weather patterns ensures maximum effectiveness[4].

Preemergent herbicides work by creating a chemical barrier in the soil. They won't kill existing weeds, so address any winter weeds like Poa annua before applying crabgrass preemergent.

Conclusion

Successful crabgrass prevention in Georgia requires precise timing based on soil temperature and your specific hardiness zone. Apply your first preemergent treatment when soil reaches 50-55°F consistently, typically late February through early March depending on your location. Monitor your lawn's response and consider a second application 8-10 weeks later for season-long protection.

Start monitoring soil temperatures in mid-February, choose a preemergent suitable for your grass type, and mark your calendar for that crucial second application. With proper timing and product selection, you can keep crabgrass from invading your Georgia lawn throughout the growing season.