How to grow Leeks
Botanically speaking, leeks are an onion relative, but they don’t form a distinct bulb. Leeks grow 2 to 3 ft tall, with an edible, mild-flavored stem that resembles a long, fat, green onion.
Start leeks off from seeds or nursery plants in very rich soil. Space seedlings 2-4 inches apart, in a 5 inch deep furrow. Leeks want full sun but will do better in part sun in hotter, inland areas. Since leeks have shallow roots, water frequently to keep soil moist.
As leeks grow, mound the soil around stalks to blanch them (this is what makes the stem bottoms white and mild). Keep mounded soil just below the leaf joints. Harvest when stems are 1 to 2 inches thick. If leeks bloom, small bulbils may appear in flower clusters; you can plant these for later harvest. Leeks are not bothered by many of the pests and diseases that attack onions.