Effective Corn Gluten Meal Application Rates for Crabgrass and Annual Bluegrass Prevention

Critical Rate

Corn gluten meal (CGM) requires **20–25 lbs per 1000 sq ft** for pre-emergent control. Standard 1 lb N/1000 sq ft rate (≈10 lbs CGM) is too low.

Timing

• Annual Bluegrass: Apply in fall (Sept) before germination; but bluegrass germinates multiple times—timing is tricky.
• Crabgrass: Apply early spring (before forsythia blooms/soil temps ~55°F).

Soil Temperature Caveat

Cool spring soils slow microbial activation of CGM. By the time it works, crabgrass may have germinated. This is why Cornell Extension is skeptical.

Fertilizer Schedule Adjustment

• Add early spring CGM application (20+ lbs/1000 sq ft).
• Cut late spring N rate in half or use slow-release.
• Maintain early fall, late fall N applications.

Spreader Setting for Agway CGM

Use small opening; pre-measure 3 lbs/1000 sq ft (e.g., 60 lbs for 20,000 sq ft). Multiple passes N/S, E/W.

Conclusion

High-rate CGM (20–25 lbs/1000 sq ft) + early spring timing + adjusted N schedule gives best pre-emergent control.