The Best Grass Killer for Green Beans

Before Planting

• Green beans are planted in the early spring when all danger of frost has passed. Before planting green beans, remove all grassy weeds from your planting area. Use a broad-pectrum herbicide that contains glyphosate. Glyphosate kills grassy weeds without leaving soil residue that harms green bean plants. This herbicide works by disrupting grassy weeds' ability to produce proteins. Spray the herbicide on a dry day so that the chemicals absorb into the foliage of your grassy weeds. Plant green bean plants five to 10 days after weeds have died.

Preemergent Herbicide

• Preemergent herbicide prevents annual grassy weed seeds from germinating. This herbicide type works by forming a chemical barrier in the soil that kills grass weeds as soon as they emerge from their seeds. Use a preemergent herbicide that contains active ingredients, such as halosulfuron. Apply the preemergent spray evenly over the planting area and not over your own turf if you plan on reseeding during the growing season. Water the green bean area, so that the herbicide sinks into the soil.

Postemergent Herbicide

• Postemergent selective herbicide kills grass without harming your green bean plants. Pick a postemergent herbicide that contains an active ingredient such as clopyralid, quizalofop or EPTC. Spray grassy annual and perennial weeds on a dry, wind-free day. You must be careful when spraying a postemergent herbicide around your turf grass. Lay down a piece of plastic before spraying to prevent harming your lawn grass. Reapply the spray during the growing season to kill warm- and cool-season weed types.

Other Considerations

• Postselective and broad spectrum herbicides are more effective when used during a 48-hour window of dry weather. Check your weather forecast before spraying, and withhold irrigation for two days. Furthermore, herbicides sprayed before a rainfall raise the risk of groundwater pollution. Focus your efforts on spraying foliage and not on the ground around your green been plants. Preemergent herbicide must be applied twice during the year. Apply preemergent spray in the spring before warm-season grasses germinate and in the fall when cool-season grass types start growing.