Corn gluten meal application, developed by Dr. Nick Christians of Iowa State University, works by making it hard for weed seeds to put down roots. The weather can have an effect on how well it works, but when applied carefully it will reduce the number of weeds that appear at the start of the season. What worries us is that some people are selling other products and calling them corn gluten meal, or are making promises for the products that just can’t be fulfilled.
Someone may tell you that corn gluten feed or distiller’s grain are the same thing as corn gluten meal. They are not, and they will not work. Even if they are putting down the real thing, you may only be getting a token amount – not nearly enough for it to do its job.
To get ANY control of crabgrass and weeds, a minimum of 15 pounds per 1000 square feet has to be applied, and the corn gluten meal has to be at least 58% to 60% protein. Some suppliers have put down as little as two pounds per 1000 square feet and mixed it into their fertilizer so it is spread over four visits! Worse, corn gluten meal only works before weeds appear so applying it late in the year isn’t going to help you much. Plus it is also a fertilizer, so once a weed has put down roots the product will only feed them – anyone who promises to kill off your weeds with corn gluten meal is selling you a bill of goods.
No matter how attractive a budget price might be, it’s no bargain if the product or application is useless.
Unless it is soaked out of the soil by heavy rains, an application of corn gluten meal can protect a lawn for five to six weeks during germination season.