Before you go dumping cornmeal all over your garden to inhibit the spread of weeds, read this. Using Cornmeal Gluten In The Garden Cornmeal is the latest natural weed killer that has been making the rounds on social media. Is it effective? Learn more.
Can You Use Cornmeal to Keep Weed Seeds from Germinating?
Advertisements In February 2019, the Facebook page “Country n garden” shared a post (archived here) borrowed from another source, which claimed that cornmeal is an effective substance in home gardens to prevent the spread of weeds:
Above an image of a metal measuring cup shaking cornmeal into a garden, text offered a purported explanation of cornmeal as weed birth control alongside a plea for engagement:
DID YOU KNOW THAT CORNMEAL IS BIRTH CONTROL FOR WEEDS? SPRINKLE IT ON YOUR GARDEN AND IT WILL KEEP WEED SEEDS FROM GERMINATING AND GROWING INTO PLANTS. REMINDER — I need your help to stay in this social network. Say something about my posts (yes, yum or will do) or I’ll completely disappear from your news feed. Appreciate your help.
The beg for likes and shares pretty clearly marked the post as engagement bait, but that alone didn’t mean that cornmeal isn’t a weed remedy. But given the popularity of the post (with a six figure share count), it also seemed like not a lot of home gardeners were aware of the purported benefits of cornmeal as a weed-discouraging substance.
The claim about cornmeal and weeds seemed to originate with Iowa State University research on corn gluten meal (a byproduct of processing cornmeal), not cornmeal itself. A March 2005 news release from that institute reported:
Corn gluten meal (CGM) is a natural by-product from the wet milling process of corn. It contains 60 percent protein and is used as a supplement in feeds for livestock, poultry and pets. The idea of spreading CGM on lawns to control weeds came quite by accident and through close observation. In 1986, Nick Christians, professor of horticulture at Iowa State University, was using CGM as a growth media in a study of turfgrass diseases. During his research, he observed that the CGM reduced grass seed germination. Curious about the possibilities, he directed his attention to finding out if and how this was possible.
Christians’ research revealed that a naturally occurring compound in the protein faction of CGM had an inhibitory effect on the root formation of germinating seeds. In 1991, he was granted a patent on CGM as a natural, preemergence herbicide for use on all crops. As a preemergence herbicide, CGM only controls germinating seeds and has no effect on weeds that are already established. Currently, it is labeled for control of crabgrass, barnyard grass, foxtails, dandelion, lambsquarter, pigweed, purslane, smartweed and several others at the time of germination.
During the past 10 years, CGM has gained national attention as being the first effective “organic” herbicide. It is marketed and distributed under several trade names.
As a weed control product, CGM is available in two forms, powdered and granulated. The powdered form is the same as that sold at mills for animal feed. Although both forms are effective, the granulated form is easier to apply.
A separate Iowa State University background page indicated that its researchers obtained a patent for corn gluten meal as a weed inhibitor in 1991. And a 1997 webpage on the same site noted that the correct form of corn gluten meal was commercially labeled and available for retail purchase — but again, it is not cornmeal per se.
But the plot thickened in 2006, when Oregon State University researchers issued a press release titled “Corn gluten meal did not prevent weeds from germinating in OSU study,” which is exactly what it sounds like:
A by-product of commercial corn milling, corn gluten meal contains protein from the corn. It poses no health risk to people or animals when used as an herbicide. With 60 percent protein it is used as feed for livestock, fish and dogs. It contains 10 percent nitrogen, by weight, so it acts as a fertilizer as well.
The use of corn gluten meal as an herbicide was discovered by accident during turfgrass disease research at Iowa State University. Researchers noticed that it prevented grass seeds from sprouting. Further research at Iowa State showed that it also effectively prevents other seeds from sprouting, including seeds from many weeds such as crabgrass, chickweed, and even dandelions. Components in corn gluten meal called dipeptides are apparently responsible for herbicidal activity.
Researchers at Oregon State University were not able to duplicate research results reported by Iowa State researchers, said OSU turf grass specialist Tom Cook.
In 2015, research from Washington State University further disputed the findings that corn gluten meal was as effective as widely believed [PDF]:
The principal researcher and patent-holder of CGM, Dr. Nick Christians, is cautious in his recommendation of CGM for weed control. He and his students and staff have published a number of papers in the scientific and popular literature. These researchers are careful to point out that CGM does not affect existing weeds, and that the nitrogen in CGM will benefit existing weeds as well as desirable plants. Therefore, inadequate weed removal prior to treatment can actually result in an increased weed problem.
CGM is not a selective product, nor is it effective on all weed types. Several species of weeds, flowers, and vegetables are inhibited by CGM, while others are not. Effectiveness in greenhouse trials generally increases with application rate (as does the cost).
Rumors about cornmeal as a weed killer or antifungal substance have apparently spread since at least 2010, when horticultural expert Dr. Linda Chalker-Scott debunked the rumors of its efficacy as baseless.
Claims that cornmeal is an effective weed inhibitor have been circulating for at least a decade. In 1991, Iowa State University patented corn gluten meal as a weed inhibitor, but cornmeal and CGM are not the same thing [PDF]. Furthermore, the the efficacy of CGM has been disputed as well.
Does Cornmeal Stop Weed Seeds From Germinating
Using Cornmeal Gluten In The Garden
Is this something you have tried? We would love to hear your successes and failure along with other suggestions for organic weed and pest control, so we can share the knowledge. Corn gluten meal (CGM), is the by-product of corn wet milling. It is mainly used to feed cattle, fish, dogs, and poultry and as a food source in some less developed areas of the world. Accidental research has found that Gluten meal is a natural substitute for chemical pre-emergent herbicides, which means it can stops weeds from germinating. There appears to be lots of evidence that shows through using this cornmeal, results in a fantastic weed killer or weed preventer. Showing that it is a great way to eradicate weeds without the threat of toxic chemicals something that we are all for here at Friendly Organics. If you have pets or small children or prefer the more natural route, gluten meal is a much safer option.
As I mentioned the weed killing attributes were discovered by accident through research carried out by Iowa State University, they were actually looking into disease research but observed that cornmeal gluten acts as an herbicide as it kept grass and other seeds, such as crabgrass, dandelions and chickweed, from sprouting.
However, it is important to note that cornmeal gluten is only effective against seeds, not plants that are mature and is most effective with corn gluten having at least 60% proteins in it. For annual weeds that are growing, plain cornmeal products will not kill it but it will help prevent their spread via seeds.
Perennial weeds will not be damaged either as their roots survive and they return each year, as mentioned cornmeal will stop their seeds becoming further plants so reducing the weeding you have to carry out. With consistent use of gluten meal products, these weeds will gradually decline and eventually you should have a weed free garden.
The use of cornmeal gluten can be extended to the lawn element of your garden as grass is a well established plant and should not be effected.. Using gluten cornmeal in gardens is a great way to keep weed seeds from sprouting and will not damage existing plants, shrubs or trees. Be sure to follow the application instructions on the package and apply before weeds start to grow. Sometimes this can be a very tight window but is best done in early spring. Be sure to wait to apply in flower and vegetable beds where seeds are sown at least until the seeds are grown up a bit. If applied too early, it can prevent these seeds from sprouting. Using Cornmeal Gluten to Kill Ants Cornmeal gluten is also a popular method to control ants. Pouring it wherever you see ants traveling is the best option. They will pick up the gluten and take it to the nest where they will feed on it. Because the ants cannot digest this cornmeal product, they will starve to death. It may take up to a week or so before you see your ant population dwindling.
Cornmeal as Weed Killer?
The quest for the perfect weed killer has led to some interesting preparations. You’ll find natural remedies that range from using boiling water to vinegar and soap. While many of these remedies work, they tend to be difficult to implement on an entire batch of weeds. They also have only short term effects.
Cornmeal is the latest natural weed killer that has been making the rounds on social media. The prospect of being able to kill weeds with a simple sprinkle of cornmeal is exciting. Most people find cornmeal to be cheap and readily available, but the real question is does it work?
What is Cornmeal vs. Corn Gluten Meal?
The biggest mistake that most people take with this natural weed remedy is running out to buy cornmeal from the grocery store shelves. The type of cornmeal that you eat is not the same as what you need for weed killing purposes.
The cornmeal in your pantry is made from ground-up corn kernels. This is what you use as an ingredient in recipes for cornbread and other dishes.
Corn gluten meal is a byproduct that is created during the wet milling process of making cornmeal. It is not meant for humans to eat, but it is sometimes used in pets and cattle feed.
Since corn gluten meal has high levels of protein, nitrogen, and oils, it is also used for lawn fertilization and weed control purposes. It is sold in lawn and gardening stores rather than at your local grocery store.
How Do People Use Cornmeal as a Weed Killer?
Corn gluten meal is found in both pellets and powdered forms. The application process involves spreading it in a specific amount that is based upon how many square feet of ground needs to be covered.
After the meal is distributed evenly on the ground, you then need to water the lawn lightly to activate the oils. If the application does work, it is only effective for around 5 to 6 weeks. Then, the meal must be reapplied.
Does It Work on All Weeds?
This method only works on weeds that have not sprouted yet. People often use it on annual weeds such as purslane. Keep in mind that it will not work on perennial weeds that have already established a root system.
How Effective Is It?
There have been multiple studies on the use of corn gluten meal as an effective weed killer with mixed results. The primary issue with this method is the difficulty of applying it at just the right time to knock out the weed seeds.
Weeds grow throughout the year in Arizona. Even annual weeds may occasionally pop up before you expect them in the spring. Once they do, this method is not effective at all. It also requires frequent reapplications. Keeping up with this method can be frustrating for busy property owners.
What Are My Other Options for Dealing With Weed Problems?
Pre-emergent sprays work similarly to corn gluten meal by suppressing weed growth at the seed level, but it is a little different. A pre-emergent spray prevents seed germination. The seeds never develop roots or sprouts.
Even if you choose to experiment with corn gluten meal, you can still expect to need post-emergent weed spraying. This method gets rid of weeds that are already visible above the ground that the meal cannot kill.
So what’s the verdict? Corn gluten meal may help with preventing weeds from emerging from your lawn. This only works if you are diligent about following the proper application process and okay with it not always working.
There are also more effective methods for getting rid of those unsightly plants. Proper weed control involves a careful plan that addresses the types of weeds that appear in your lawn at every stage of growth.