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Corn gluten meal could be your solution to weed control this year.
Weeding: the organic way
By Deb Brown
From eNews, September 2, 2004
If you're thinking about weed control strategies for your lawn this year, how about trying an "organic" approach? Corn gluten meal, a by-product of the corn milling process, has been found to interfere with seeds' ability to germinate. The product is also beneficial because it adds nitrogen to the soil as it breaks down, so it fertilizes the lawn and helps grass grow more vigorously.
If you've already started using corn gluten meal to prevent weed seeds from sprouting--or if you'd like to begin an organic lawn care routine--apply corn gluten meal to your lawn now (early September). Then follow through with another application next spring--late April or early May.
Spread the product at a rate of 20 pounds per thousand square feet, then water it into the soil to activate it. You'll get the best weed control after using the product in both spring and late summer for three or four consecutive years. Results should improve each year, then level off after several years.
Corn gluten meal is effective against a broad range of weed seeds, not just crabgrass and other annual weeds. But it cannot tell the difference between weed seeds and grass seeds. So, if you apply it in August or September, you won't be able to seed your lawn until the following spring.
Corn gluten meal won't help as much with broad-leaf perennial weeds such as dandelions, plantain, or creeping charlie (ground ivy). It only works to stop their seeds from sprouting. It doesn't damage existing plants. Plan to pull or dig those broad-leaf weeds this fall after a heavy rain when the ground is soft. That way, they won't be around to bloom next spring or produce more seeds and seedlings.
Corn gluten meal is available at garden centers and hardware stores.
Deb Brown is a horticulturist with the University of Minnesota Extension Service.