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ALLIUM porrum

Image of Allium porrum

Jessie Keith

Family

Liliaceae

Botanical Name

ALLIUM porrum

Plant Common Name

Garden Leek

General Description

Leeks have a delicate, sweet oniony flavor that cannot be matched, and though they take a bit more work to cultivate, they are well worth growing. Unlike onions, their leaf bases are eaten as well as the bulbs. They are technically short-lived perennials but are grown as annuals. The species of wild leek from which they are derived, Allium ampeloprasum, originates from southern Europe, North Africa and regions in the Middle East where they grow in sandy coastal spots as well as open pine forests. Contemporary leeks are most commonly grown and eaten in the western world and are essential to many European cuisines.

Leeks are upright and have broad, flattened blue-green to gray-green leaves that arch and are pointed at the tips. The leaves overlap to create the long stem base that’s eaten. The base of the leek is white and slightly bulbous—kind of like an elongated onion. Leeks produce surprisingly pretty flowers in the spring of their second year. The perfectly round flower clusters rise from tall, leafless stems. A single plant will typically produce one flower head comprised of lots of white, starry flowers. Occasionally the heads will have small bulbs (bulbils) instead of flowers. These can be planted in the ground to produce leeks the following year.

If grown in full sun and organic-rich, well-drained soil, leeks will thrive. Sandy loam is ideal. They perform best if given light supplemental nitrogen and grown in areas with cool, pleasant summers. Regular water is needed if conditions become too dry. There are several problematic pests and pathogens that damage leeks. Onion flies and leek moths can infest the bulbs and stems and white rot can be a problem—especially in poorly drained soils.

Leeks are planted in spring as either bulbils or seedlings and are typically grown in mounds. Seedlings should be planted at a depth that’s two or three times their width. As the plants grow, keep the soil mounded around their stems up to the lowest leaf joint. This process is called blanching and will produce a longer, more tender white stem for cooking and eating. Leeks can be harvested when they are a half an inch to two inches thick (one to six centimeters) or after 120 to 210 days of growth. It is preferable to harvest them before the soil freezes. Any small, uprooted leeks that are not ready can be replanted.

Characteristics

  • AHS Heat Zone

    7 - 1

  • USDA Hardiness Zone

    6 - 9

  • Sunset Zone

    A3, H1, H2, 1a, 1b, 2a, 2b, 3a, 3b, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24

  • Plant Type

    Vegetable

  • Sun Exposure

    Full Sun, Partial Sun

  • Height

    1'-3' / 0.3m - 0.9m

  • Width

    1'-2' / 0.3m - 0.6m

  • Bloom Time

    Spring, Late Spring

  • Native To

    Europe, Northern Africa, Western Asia

Growing Conditions

  • Soil pH

    Acidic, Neutral

  • Soil Drainage

    Well Drained

  • Soil type

    Loam, Sand

  • Growth Rate

    Fast

  • Water Requirements

    Average Water

  • Habit

    Clump-Forming

  • Seasonal Interest

    Spring, Summer, Fall, Winter

Ornamental Features

  • Flower Interest

    Showy

  • Flower Color

    White

  • Fruit Color

    Tan

  • Foliage Color (Spring)

    Green, Blue Green, Gray Green

  • Foliage Color (Summer)

    Green, Blue Green, Gray Green

  • Foliage Color (Fall)

    Green, Blue Green, Gray Green

  • Fragrant Flowers

    Yes

  • Fragrant Fruit

    No

  • Fragrant Foliage

    Yes

  • Bark or Stem Fragrant

    Yes

  • Flower Petal Number

    Single

  • Repeat Bloomer

    No

  • Showy Fruit

    No

  • Edible Fruit

    No

  • Showy Foliage

    Yes

  • Foliage Texture

    Coarse

  • Foliage Sheen

    Matte

  • Evergreen

    No

  • Showy Bark

    No

Special Characteristics

  • Usage

    Edible, Herb / Vegetable

  • Sharp or Has Thorns

    No

  • Invasive

    No

  • Attracts

    Butterflies

  • Self-Sowing

    Yes