How would you like to weed your lawn, feed it at the same time, and not give a second thought to your kids or pets playing on the grass moments later? You can, with products based on corn gluten meal. For most gardeners, now, early spring, is a good time to buy so you can apply it before weeds germininate.
Corn gluten meal is a byproduct of corn syrup production, and is used routinely as a nutritious additive in foods for farm animals and pets. Yet it stops seeds of weeds like dandelions, pigweed, crabgrass, plantain, lambs quarters and curly dock in their tracks. On top of that, it contains about 6 percent nitrogen which is released slowly, by soil microorganisms, over the course of the season. (For more, see "Organic Fertilizers.") For this one, natural material to both prevent weeds and feed your lawn is a far cry from the high-tech combinations of sometimes toxic chemicals manufacturers have concocted for the same purpose.
The discovery was serendipitous. Dr. Nick Christians at Iowa State University made the discovery in the course of other research in 1986. He was awarded a patent for corn gluten meal as an herbicide in 1991, and the Gardens Alive! company was the first to market the product in 1996. To say it's been well-received is an understatement. Researchers are continuing to study exactly how it works, and to develop new formulations, such as hydrolyzed proteins from corn and other grains.
Corn gluten meal is a pre-emergence herbicide meaning that it prevents weed roots from growing properly and becoming established. Any weed that has germinated and formed a root will not be effected, meaning timing is important. Using either a drop or broadcast spreader, apply 10 pounds per 1,000 square feet of lawn in spring and again in fall. It's ability to block weed growth lasts about a month. Research has shown that these two applications will reduce crabgrass in a Kentucky bluegrass lawn by half or more the first year, and that weed control improves each successive year you use it.
Corn gluten meal also appears to be very promising for controlling weeds in strawberry patches and could be used in perennial beds or anywhere you plant well-established transplants. Apply the meal to soil immediately after tilling and carefully work it into the top 2 to 3 inches of soil.
You can buy dry and granular corn gluten meal under various trade names, such as W.O.W.! Plus, Dynaweed, BioWeed Natural Weed Control, Safe 'N Simple, Earth Friendly, and Concern-Weed Prevention Plus. It is the same corn meal sold at feed mills for animal feed, but in a granular form which makes application much easier. The cost is about $30 for 25 pounds, and $50 for 50 pounds.
Michael MacCaskey is editorial director at National Gardening.
Article published on June 23, 2008.