Allium ampeloprasum (Porrum Group)
Common Name: leek
Type: Annual
Family: Amaryllidaceae
Native Range: Temperate regions
Zone: 2 to 11
Height: 1.50 to 3.00 feet
Spread: 1.00 to 1.50 feet
Bloom Time: Rarely flowers
Sun: Full sun
Water: Medium
Maintenance: High
Suggested Use: Annual, Vegetable
Tolerate: Rabbit, Deer

Culture

Easily grown in deep, organically rich, medium moisture, sandy, well-drained loams in full sun. Plants perform best with consistent moisture during the growing season.

For Porrum Group plants (leeks), turn over soil to 6" deep in early spring and work in manure and compost. Planting options include (1) seed may be started indoors about 8-10 weeks prior to last spring frost date, with plants set out in the garden about 3 weeks before last spring frost date, (2) transplants may be purchased for setting out in the garden about 3 weeks before last spring frost date or (3) seed may be sown directly in the garden 1/4" deep in rows 12-18" apart about 3 weeks before last spring frost date. Thin plants to 4" apart. Add a balanced fertilizer. In order to produce the best white stems which are the signature of leeks, lower plant stems must be blanched (hidden from sun). This is commonly done by (1) planting leeks in 6" deep furrows/trenches with subsequent addition of soils around the bases of each plant as the stems grow upwards until trench soil levels reach ground level or (2) mound or hill soil around the cylindrical stem of each plant base. Harvest plants when the lower stems reach 1-1 1/2" in diameter.

Noteworthy Characteristics

Allium ampeloprasum, commonly known as wild leek, is in a large genus of about 400 species of variable plants in the onion family. This species is native to Southern Europe, northern Africa, western Asia and Egypt, but has been introduced and in many cases naturalized in a large number of additional areas throughout the world. This species consists of biennial, onion-like plants now divided into three different horticultural/vegetable groups, namely (1) Porrum Group (leeks grown for their tasty stems), (2) Ampeloprasum Group (elephant garlic and levant garlic grown for their mild garlic-like bulbs) and (3) Kurrat Group (kurrat).

Porrum Group plants are the leeks which are very popular biennial plants primarily grown in the U. S. in vegetable gardens as annuals. Overall, plants typically grow in a fan-like structure to 12-30" tall and to 12" wide. These plants feature a stalk and leaves which have a delicate, sweet and mild oniony flavor without the pungency of some other types of onion. The edible part of the plant is not an underground bulb (leeks do not form bulbs), but is the cylindrical white stalk that rises about 6-10" above the soil surface. Encircling blue-green leaves form the stalk at the base, but branch outward at the top to form fans of flat (not hollow like onions) green leaves. Leaks have a mild, onion-like flavor. Species is biennial (purple, pink to white flowers only appear in the second year in spherical clusters). When grown as annuals, flowers will never be seen.

Genus name comes from the classical Latin name for garlic.

Specific epithet comes from the Greek word ampelos meaning vine and parson meaning leek for a leek found growing in vineyards.

Problems

No serious insect or disease problems. Bulb rot may occur in overly moist soils. Slugs attack young plants. Rust may be the most serious disease affecting leeks (remove and destroy infected plants). Watch for mildew and leaf spot. Onion maggots and thrips may appear.

Garden Uses

Vegetable commonly added to casseroles, salads, stir fry, soups and stew, but may be eaten raw. Important ingredient in the French soup vichyssoise.