Fall Pre-Emergent

Fall is one of the most important times to apply pre-emergent herbicides—especially for warm-season lawns. As soil temperatures drop in late summer and early fall, weed seeds like poa annua, chickweed, and other winter annuals begin to germinate. Applying a fall pre-emergent creates a barrier that stops these weeds before they sprout, keeping your lawn clean and healthy through winter and spring.

When to Apply Fall Pre-Emergent

The best time to apply fall pre-emergent is in early September when soil temperatures are between 70–75°F and beginning to cool. This is the window when poa annua (annual bluegrass) and other broadleaf weed seeds start to germinate. Applying pre-emergent at the right time blocks these weeds before they ever become visible in your lawn.

Important: Do Not Use Pre-Emergent If Overseeding Cool-Season Grass

If you're overseeding in the fall, do not use pre-emergent. These products form a barrier in the soil that will prevent all seeds from germinating—including your grass seed. Wait until after new grass is established (typically 4-6 weeks) before using any weed control products.

Best Pre-Emergent for Fall Lawns

We recommend Guardian™ 13-0-10 with Prodiamine for fall pre-emergent control. It's ideal for warm-season lawns like Bermuda and Zoysia that are not being overseeded. Guardian contains:

• Prodiamine: Trusted pre-emergent active that blocks weed seed germination
• 13% Nitrogen: Encourages strong, green growth while temperatures are still warm
• 10% Potassium: Improves disease resistance and root strength heading into winter

This dual-purpose formula feeds your lawn while protecting it—making it a smart and efficient fall application.

How to Apply

• Apply with a broadcast spreader at 5 lbs. per 1,000 sq. ft. rate
• Water in with at least ½ inch of irrigation within 48 hours
• Do not aerate or disturb the soil after application

Ideal For:

• Warm-season lawns (Bermuda, Zoysia, St. Augustine)
• Homeowners who are not overseeding in fall
• Blocking poa annua, chickweed, henbit, and other winter weeds