Poa Annua in St. Augustine: Heat Treatment and Prevention

Summer Heat Kill (No Chemicals)

When temps hit 90s+, stop watering for 10 days. St. Augustine survives; Poa annua (shallow roots) dies. Resume deep watering—St. Augustine recovers.

Floratam ID

Can't visually distinguish Floratam from other St. Augustine. Test a small patch with any questionable product—if it lives, you're safe.

Pre-Emergent for Next Year

• Apply in fall (Sept–Oct) before Poa germinates.
• Products: prodiamine, dithiopyr, atrazine (check label for St. Augustine).
• Reality: Soil seed bank is huge—pre-emergent reduces but won't eliminate.

Long-Term Strategy

Thick, healthy St. Augustine (mow 3–4", fertilize moderately, water deep) is your best defense. Poa invades thin, overwatered, overfertilized turf.