Corn gluten meal is a natural byproduct of corn wet-milling process and has been found to kill weeds as they germinate. It will also harm the germinating seed of desirable plants. It has no effect on weeds that are already present or on existing desirable plants. It also is a fertilizer with 8% nitrogen. There are a number of commercially available products including Wow Supreme, Organic Weed Preventer, Corn Gluten Weed Preventer, Weed Prevention Plus and Corn Gluten Organic Fertilizer. Check labels carefully before purchase as some products are only labeled for lawns while others are also labeled for flower and vegetable gardens as well as landscaped areas.
Apply before weed germination. For a spring application, apply when the forsythia begins to bloom. Expect a 50 to 60% reduction in target weeds the first year with effectiveness increasing the next couple of years with continued use. The product is more expensive than traditional preemergence herbicides but may be useful to those who wish to avoid synthetic herbicides and fertilizers. (Ward Upham)