Apply corn gluten meal as an organic pre-emergent

What to Do

Spread corn gluten meal at 20 lbs per 1,000 sq ft in mid-spring, timed to coincide with when you would apply synthetic pre-emergent (soil at 55°F).

Why It Works

Iowa State University research found that corn gluten meal inhibits root formation in germinating seeds. It also provides 9-10% slow-release nitrogen as it breaks down. It is the only organic option with documented pre-emergent activity.

Tips

• Effectiveness is modest — 50-60% weed suppression compared to 90%+ for synthetic products.
• Must be applied before weed seeds germinate and needs dry conditions after application to work.
• At $30-80 per 1,000 sq ft, it costs 5-10x more than synthetic pre-emergents.
• Best for lawns transitioning to organic care with already-low weed pressure.