A study was done to see how different herbicides affect weed control in winter onions. The best results came from using two herbicides in a row: pendimethalin followed by oxyfluorfen. This combo controlled grasses, sedges, and broad-leaf weeds well, leading to high onion yields. In plots without herbicides, weeds caused a 54.8% loss in onion yield. The best herbicide combo also reduced total weed density and weight, while increasing onion yield and cost-effectiveness. In weedy plots, the weeds took up a significant amount of nutrients from the soil.