nderused and overpriced in the US the leek has long been a staple in European kitchens. The sweet, mild onion flavor of leeks makes them a versatile addition to many recipes. Leeks can be used as the key ingredient in foods or blended without overpowering the other flavors in a dish. Leeks are a heirloom that has been grown for literally hundreds of years. 120 days. Approximately 325 seeds per 1/32 ounce packet.