Oh dear, and I think that advice is mentioned in my OG book but not Winter Vegetables. I now realise it is not the best way, is too radical, hurts the plant too much. Loss of all leaves from cutting means regrowth is slow. It seems that leek moth is here to stay and we just have to accept it. Early, fast growing varieties like King Richard for summer eating and Autumn Mammoth for autumn and beyond are good for growing away from moth damage, when sown in March indoors in modules or early-mid April outdoors, in rich soil, a necessity for good leeks.