Does Corn Gluten Really Prevent Weeds?

“What is your opinion of using Cornmeal Gluten to prevent weeds starting from seeds?” Question from Kathy of Loomis, California

Answer: Corn gluten is a popular all-natural pre-emergent herbicide that will stop the germination of certain seedlings when properly applied. That means that it keeps weed seeds from sprouting. For this reason, it is important to apply it well before cool-season weed seeds get going in late winter and spring and warm-season weed seeds get going in summer.

Corn gluten is an all-natural byproduct of the corn industry. Essentially, it is comprised of corn protein. For this reason, it is not harmful to people or wildlife, while stopping some weed seeds from sprouting. With that said, there are some different opinions and studies with varying reports on its efficacy. Here are the two sides.

Corn Gluten As a Pre-Emergent Herbicide

A 1990s Iowa State University study showed that corn gluten was an effective pre-emergent herbicide for some weeds. They found that it was most effective in stopping weedy grasses, such as crabgrass, as well as some broadleaf weeds, such as chickweed and dandelions. Corn gluten also contains 10% nitrogen, so it helps feed plants as well.

Corn Gluten’s Herbicidal Short-Falls

Some studies show corn gluten, when not properly applied at the right time, can feed weeds due to its high nitrogen content. That’s because it does not negatively impact emerged weeds, so these will need to be hoed out or hand-weeded before applying any pre-emergent. It is also important to note that corn gluten does not work on all weed seeds. A Washington State Univerisity overview of corn gluten states: “Corn gluten meal is not a selective product, nor is it effective on all weed types. Several species of weeds, flowers, and vegetables are inhibited by corn gluten meal, while others are not. Effectiveness in greenhouse trials generally increases with [the] application rate (as does the cost).”

As for me, I rarely apply pre-emergents. This is because I favor various mulches and hand weeding to stop weeds in my gardens. For me, these are the two best methods to keep weeds away. Here is an article along these lines.



I hope that this helps!

Happy gardening,

Jessie Keith

Black Gold Horticulturist


Plants are the lens Jessie views the world through because they’re all-sustaining. (“They feed, clothe, house and heal us. They produce the air we breathe and even make us smell pretty.”) She’s a garden writer and photographer with degrees in both horticulture and plant biology from Purdue and Michigan State Universities. Her degrees were bolstered by internships at Longwood Gardens and the American Horticultural Society. She has since worked for many horticultural institutions and companies and now manages communications for Sun Gro Horticulture, the parent company of Black Gold. Her joy is sharing all things green and lovely with her two daughters.

Leave a Reply

Content Disclaimer:

This site may contain content (including images and articles) as well as advice, opinions and statements presented by third parties. Sun Gro does not review these materials for accuracy or reliability and does not endorse the advice, opinions, or statements that may be contained in them. Sun Gro also does not review the materials to determine if they infringe the copyright or other rights of others. These materials are available only for informational purposes and are presented “as is” without warranty of any kind, express or implied, including without limitation warranties of merchantability, fitness for a particular purpose, and non-infringement. Reliance upon any such opinion, advice, statement or other information is at your own risk. In no event shall Sun Gro Horticulture Distribution, Inc. or any of its affiliates be liable to you for any inaccuracy, error, omission, fact, infringement and the like, resulting from your use of these materials, regardless of cause, or for any damages resulting there from.