These larger versions of green onions have a more flavorful and milder taste. Leeks are members of the onion family, closely related to onions, garlic, shallots and chives. Leeks, unlike onions, develop long, succulent stems rather than producing large bulbs.
The best place for growing leeks is in full sun in fertile, well-drained soil. As the leeks grow, slowly build up soil around the stem to keep out light which will blanch the stalks and keep them from being green at the base. Once plants reach a diameter about the size of your thumb, you can begin harvesting leeks. Be sure to harvest leeks before flowering occurs.
Leeks are best used right away; however, they can be stored in the refrigerator for several weeks.
Read more about growing bulbing onions here.