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Chemical-free Corn Gluten Meal Kills Weeds, Feeds your Turf and Doesn't Threaten People and Pets!
Q. Dear Mike: PLEASE HELP! My lawn is in terrible shape. The crab grass last year was horrible, as were other weeds. I have used Scotts in the past but nothing last year, when I decided to go completely organic for my cats, who are constantly eating the grass. What do you recommend?
---Eileen; just outside of Philadelphia
Can you help me take care of my lawn—preferably organically? My late husband used to do all this for me; he put something on in March—a "pre-emerge" that helped keep a lot of the dandelions and other weeds from sprouting. I still have the drop spreader he used. I didn't do anything last Spring, and I thought the dandelions were going to takeover the front yard, but then the rains brought the Bermuda grass into its own, and it just grew those dandelions out of a home!
---Earlie in central Oklahoma
My husband and I moved into a new home last year. Despite having used Scott's lawn service since they laid our sod, we have lots of weeds—as well as bare spots that need reseeding. More importantly, we have 2 children and I am 7 months pregnant with our third. I would like to try Corn Gluten Meal to control the weeds, but I'm afraid it might prevent the grass seed from germinating. Please give us some guidance. Thanks!!
---Susan in Maryland
A. And that's just the tip of the lawn care/corn gluten meal iceberg in our email box!
First, the basics. A decade and a half ago, Iowa State University turf grass researcher (and frequent YBYG guest) Dr. Nick Christians accidentally discovered that corn gluten—the protein-rich component left over after they make cornstarch—prevented seeds from germinating successfully. Now, he already knew that corn gluten would make a great lawn fertilizer—it's a whopping 10% nitrogen, the food that grass craves the most. (Ten pounds of corn gluten spread on 1,000 sq feet of turf supplies a full pound of lawn - lushing nitrogen!)
But this new discovery meant it would also kill Spring time weeds—thus creating an all-natural replacement for the toxic chemical weed and feed products that threaten people, pets and the environment. (Some herbicides in chemical weed and feeds have been linked to increased rates of cancer in people and dogs, and their harsh chemical fertilizers cause huge problems in environmentally sensitive areas like the Chesapeake Bay.) Corn gluten received a federal patent as a natural pre-emergent herbicide in July of '91.
As with chemical per-emergents, Nick explains that timing is everything. Right now, the seeds of crabgrass and many other weeds are lying dormant in your lawn, just waiting for warm weather to germinate. But if you spread 10 to 20 pounds of corn gluten meal per thousand square feet of lawn when the first yellow blooms appear on for sythia bushes in early Spring, you'll prevent those early season weeds from sprouting successfully.
Yes, corn gluten does prevent the successful germination of all seeds, so you can't reseed any bare spots or sow a new lawn when you use it. But Spring is NOT the best time to do such things anyway; you have a much better chance of success in the Fall. If you MUST fix a spot or two this Spring, get the gluten down early—when the first Spring bulbs appear. Then you can safely sow grass seed six weeks later, when the gluten will have lost its herbicidal effect. (But I wouldn't bother if you have a spreading type of grass, like Zoysia or Kentucky blue; it should fill in bare spots without any help once you begin taking proper care of your turf.)
Technically, perennial weeds like dandelion, red clover, fox tail and bent grass shouldn't be affected, because they're already there. But apparently nobody told the corn gluten. The Iowa State researchers noticed that these—and other—really tough weeds became scarcer and scarcer in their test plots year after year, until by year three or four they were gone or reduced to very minor levels. Nick feels that some of this is due to the prevention of new weed seeds from sprouting, but attributes the main effect to the fact that corn gluten's natural slow-release nitrogen helps grass grow the kind of strong roots that crowd weeds out. As our Oklahoma listener notes, happy grass beats the worst weeds.
Corn gluten meal comes in powder and granulated forms; granulated works best in conventional spreaders. Gardens Alive, which sells both under the brand name "Wow" (for 'With Out Weeds'), was the first company to license corn gluten from Iowa State, and the company that registered it as a natural pre-emergent herbicide with the EPA.
Retail? Nick Christian's corn gluten page at Iowa State (https://www-hort.sws.iastate.edu/research/gluten) lists every company that has a current license to sell the product. And here's a great scientific article about CGM that's easy to read and goes into lots of detail—especially about the weeds it affects: https://www-hort.sws.iastate.edu/sites/default/files/imported/gluten/pdf/cornglut3.pdf
To get the best results, water it in really well and then allow the area to dry out. Any weed seeds that try and germinate will be killed naturally by the gluten. Then it will slowly release its lawn feeding nitrogen to build up the kind of healthy turf that naturally resists—or just plain kills—weeds without any direct herbicidal help.
…as long as you care for your grass properly, that is. Most people don't. So we'll reveal the rest of what you need to know to have a weed-free lawn without any chemicals (and with a lot less work than you're probably doing now!) next week…