This Natural Herbicide Might Help Stop Weeds Before They Start, But Only If You Use It Right

While there are some useful common weeds you may want to consider leaving in your yard, in general, most homeowners are on a never-ending quest to vanquish them from their garden for good. It's even better when the weed solution is free of harmful chemicals, which is likely why corn gluten meal is so popular. Not to be confused with cornmeal (a food-grade product used in cooking), corn gluten meal (CGM) is a byproduct of corn processing with an incredibly high protein content that can offer herbicidal uses, and was patented as a weed-killer in 1991.

CGM does have its limitations, however, and in order for it to do its job successfully, you need to get your timing and tact just right. CGM works best as a pre-emergent herbicide, meaning it can literally nip weeds in the bud before they have a chance to develop roots. This means that in order to be effective, CGM needs to be applied in early spring, before weeds have an opportunity to germinate. After applying, the CGM then needs to be watered into the soil within five days of applying, followed by one to two dry days. And when you're finished, don't expect to see results right away; the first attempt may not suppress all the weed seeds, and it may take several applications throughout the season or on a monthly basis before it works well.

You'll also want to be strategic about which types of weeds you try to tackle. CGM is currently labeled for control of several common weeds, including crabgrass, foxtails, and dandelions, among others. Since CGM is a pre-emergent herbicide, use it to target annual weeds as opposed to perennial ones, as annual weeds propagate only through seeds.

The University of New Hampshire notes that while some gardeners swear by corn gluten meal, research on its efficacy at combating weeds is mixed. Some studies have found that it is actually not very effective against crabgrass, for example. In another study, researchers at Washington State University found it made no difference in weed control for field-grown strawberries, and that the high protein content of CGM may even increase the need for additional weeding. 

CGM also isn't selective in what it prevents from growing. While it can prevent weed seeds from growing, it can also prevent other seeds, like turf seeds, from growing, too. You certainly don't want to kill off your lawn in the process, so be sure to only use CGM on established lawns, not on newly-seeded grass.

Perhaps one of the biggest limitations is that CGM cannot get rid of existing weeds or weeds that have already begun to germinate, so you'll have to look for other methods for tackling weeds if they pop up. For weeds that have already sprouted, you can try this removal tip that'll prevent weeds from taking over your lawn, which involves decapitating any weeds that pop up so that they can't propagate. Otherwise, you'll want to find a post-emergent weed-killing solution. You can even create your own when you whip together some common kitchen items for Martha Stewart's 3-ingredient DIY weed killer, which eliminates grown weeds on contact.