Crabgrass is one of the most prevalent and troublesome weeds in the home vegetable garden. If it is allowed to grow uncontrolled, it can shade out and prevent corn from growing past the seedling stage. In addition, crabgrass uses up the water and nutrients that growing and mature corn needs to thrive and produce a plentiful harvest. Although crabgrass is one of the toughest weeds to get rid of, with a few techniques and perseverance, you can control and get rid of most crabgrass.
Cultivate or break up the soil with a hoe or tiller to kill crabgrass seedlings before you plant the corn. After the corn grows, continue to cultivate the soil between the rows whenever crabgrass begins to grow, usually once every two weeks. This will help eliminate some of the need for hand pulling. Avoid cultivating near the base of the plants where you can cause irreversible damage.
Pull crabgrass and other weeds at least every two weeks for immediate results and to control its growth and spread, especially between and around corn plants. Grab the crabgrass at the base and pull up slowly to get up the long viney root. Pulling weeds is easier when the soil is moist.
Apply an herbicide. Along with regular weeding and cultivating the soil, apply a post-emergent herbicide, such as Poast, on actively growing crabgrass. Also, apply a pre-emergent herbicide, such as Dacthal, before the crabgrass grows in the spring or directly after you weed to prevent more from growing. Every herbicide is different and is applied with a different dilution rate. Ready-to-spray bottles are easiest. Reapply as needed, usually every three to four weeks, as indicated on the label.