Leeks are root vegetables that look quite similar to onions, to which they are related. Their flavor is onion-like but much milder. Unlike onions, leeks don't form much of a bulb on the end of the root. Instead, they remain cylindrical, with perhaps a slight bulge at the end. The leek is a vegetable that belongs, along with onion and garlic, to the genus Allium, currently placed in family Amaryllidaceae, subfamily Allioideae. Historically many scientific names were used for leeks, which are now treated as cultivars of Allium ampeloprasum.
- Lincoln (OP)
- King Richard
See the Soil Fertility sections for Onions.
For best results, leek seeds should be sown in the greenhouse about 2.5 months before field setting. About 2 to 3 lb of seed are needed to raise enough plants to set an acre at average spacing (0.25 to 0.5 oz per 100 feet of row). Before setting, clip plants to a height of 3" to reduce wind damage in the field. Set plants in the field from late April to late May depending on location and earliness desired. Plants can be set in early July for a late fall harvest, or in milder locations, growers may wish to try overwintering leeks using a straw mulch. Rows can be from 15" to 30" apart depending on equipment; plants should be about 3" to 6" apart (200 to 400 plants per 100 feet of row)
To develop a long, white stem, leeks can be planted in a trench 3" to 4" deep. The trenches are gradually filled as the leeks grow and then soil is hilled around stems to a height of 3" to 4". Soil particles have to be cleaned from the leeks when preparing for market. Self-blanching varieties are grown without trenching and hilling and require less cleaning.
Harvest and Storage
Leeks can be harvested once the base reaches at least 1" diameter. Optimum storage conditions are 32° F with 95 to 100% relative humidity, to prevent wilting. They should be kept away from crops that produce ethylene.