Guest post by Deb Brown
From the calls I've gotten, it's clear there's some confusion about corn gluten meal and its ability to control weeds in the lawn. Although it's a natural product, safe enough to feed cattle, it's not a miracle cure for a weedy lawn.
Corn gluten meal works in two ways: It inhibits seed germination, preventing many weed seeds from sprouting. It also delivers an organic source of nitrogen to the soil as it breaks down, feeding existing plants.
Corn gluten meal does not kill existing weeds, both perennial weeds (such as dandelions, creeping Charlie and quackgrass), which come back from their roots each spring, or annuals (such as crabgrass, knotweed and purselane), which have already emerged from the soil. Once a weed is up and growing, corn gluten meal is completely ineffective against it. What it does is prevent seeds from sprouting.
When applied in spring and again in late summer for two or three consecutive years, your lawn will improve. It'll likely be thicker and healthier lawn, which makes it harder for weed seeds to take hold. However, if you use corn gluten meal, you'll still have to deal with perennial weeds by digging them out or using a weed killer. (Which weed killer you use depends on what type of weeds you have. Read the label carefully.)
