Baking Soda on Lawns: Use Selectively, Not as Routine Weed Control

Homeowner tried baking soda on crabgrass—killed some, yellowed surrounding grass, crabgrass returned. Asks if it harms soil organisms.

Baking Soda = Salt (Sodium Bicarbonate)

• Alters pH on leaf surface → inhibits some fungi.
• Damages grass blades (yellowing observed).
• Kills beneficial soil microbes—disrupts natural disease suppression.
• Does NOT kill established crabgrass (only burns top growth).

Better Alternative: Corn Gluten Meal (CGM)

• No salt. Pre-emergent: stops seed germination.
• Decomposes to slow-release nitrogen.
• Apply at forsythia bloom (spring).

Cornmeal vs. CGM

• Cornmeal: Feeds beneficial fungi (Trichoderma) that attack pathogens.
• CGM: Protein fraction of corn; weed suppressor + fertilizer.
• Different products—don't confuse.

Verdict

Keep baking soda for mildew on roses or spot fungus on lawn. Never broadcast for weed control. Use CGM for prevention, cornmeal for disease, compost for soil health.