Corn Gluten is a great way to control annual weeds in the lawn including crabgrass. It should be applied in early spring. Corn Gluten should be applied to lawns early in the spring just as they are beginning to green. I like to apply mine April 1st and again in mid-May. I find that two applications per year works quite well in controlling many weeds. Remember that you can not plant new grass seeds where you have applied corn gluten as the seed will not germinate...