Corn gluten meal is an effective organic herbicide.
Corn gluten meal is not an effective organic herbicide; although; since it inhibitsgermination of any seed, it can help to keep annual weeds in check. And, applying it after the weeds are up and growing will only feed them. There are no scientific data to support the use of CGM in weed control. Other environmentally friendly weed-control treatments (such as sub-irrigation, mulch, or soil solarization) are cheaper and often more effective than CGM. Try it and draw your own conclusion.