Abstract Three field studies were conducted to determine the selectivity on leeks ( Allium porrum L.) of early post-transplant herbicides and their efficacy on weed populations and crop yields. Herbicide treatments were cinmethylin, metolachlor, oxyfluorfen, prodiamine, and pendimethalin. Both a non-treated and a weed-free control were added. The most common species were the broadleaved weeds Eclipta alba (L.) Hassk. , Rorippa teres (Michx.) Stuckey, Geranium carolinianum L., Amaranthus viridus L., and Solanum americanum P. Mill., while Paspalum distichum L. was the most predominant grass species. The herbicides providing the most consistent season-long weed control were metolachlor, oxyfluorfen, prodiamine, and pendimethalin. Plots treated with metolachlor, prodiamine, and pendimethalin had the highest yields and plant vigor and were comparable to those for the weed-free control plots.