Leek

Sun

Full sun; tolerates light shade with slower growth.

Water

Keep evenly moist, especially after transplanting and while stems are thickening; avoid waterlogged soil.

Soil

Deep, fertile, moisture-retentive but well-drained soil, ideally pH 6.0-7.5.

Height

1.5-3 ft (0.45-0.9 m) in leaf; flowering stems can reach 4-5 ft (1.2-1.5 m)

Spread

0.5-1 ft (0.15-0.3 m)

Flowers

Rounded heads of white to pale pink flowers in late spring or summer of the second year, if left unharvested.

Foliage

Long, flat, overlapping green to blue-green leaves form a thick, pale false stem rather than a rounded bulb.

Growth

Moderate; usually takes about 4-7 months from sowing to harvest, depending on variety and conditions.

Care needed

Medium

• Pollinators
• Low allergen
• Edible

Northern hemisphere months. In Australia, shift them by six.

Difficulty

Moderate

Toughness

Fairly tough

Pick your zone, country, light and whether you have pets.

1. Planting day

   0.5 ft (0.15 m)

2. After 1 year

   2.2 ft (0.68 m)

   full size

Full size in one season.

From a typical nursery size, at an average rate for this kind of plant. A rule of thumb, not a forecast.

Cats and dogs

Toxic

Growth rate

Moderate

• Space transplants 6-8 in (15-20 cm) apart, with room between rows for weeding and earthing up.
• Water deeply during dry spells so the root zone stays moist.
• Work compost into the bed before planting; feed with a nitrogen-rich vegetable fertiliser once plants are established.
• Draw soil gradually around the stems to blanch them, keeping soil out of the leaf joints.
• Mulch between plants to conserve moisture and suppress weeds; keep mulch away from the central leaves.

Pruning. No routine pruning is needed. Remove badly damaged leaves and cut out flower stalks promptly unless saving seed; flowering makes the central stem tough.

Harvest whole leeks when the white and pale-green shanks are about 1 inch (2.5 cm) thick, usually 3–5 months after transplanting; smaller leeks can be picked earlier. Loosen the soil with a garden fork and lift gently rather than pulling, then trim the roots and tough leaf tops. Harvest from late summer into winter according to variety and planting time;

Late winter

In cool climates, sow seed under cover for a long growing season.

Spring

Prepare the bed with compost and transplant sturdy seedlings once the soil is workable.

Early summer

Keep young plants weed-free, water during dry weather and begin feeding once established.

Summer

Earth up stems gradually and inspect leaves for rust and insect damage.

Autumn

Harvest as stems reach a useful thickness; in mild-winter regions, plant locally suitable varieties for a cool-season crop.

Winter

Lift winter-hardy varieties as needed where the ground is not frozen; harvest before severe cold in colder regions.

• Plant in straight rows in a potager for strong vertical lines among rounded lettuces and cabbages.
• Use small groups in edible borders for their blue-green, strap-like foliage.
• Grow in deep raised beds where fertile soil and easy access simplify harvesting.
• Leave a few plants to flower at the back of a kitchen garden for rounded flower heads visited by insects.

Garden styles it suits: Potager (kitchen garden), Edible landscape, Homestead, Cottage garden, Formal and Family-friendly.

Plant it with: Carrots, Lettuce, Beetroot, Swiss chard, Cabbage and Calendula.

Wildlife: Flowers attract bees and other pollinating insects if plants are allowed to bloom in their second year.

• Leek moth: caterpillars tunnel into leaves and stems. Cover crops with insect mesh before egg-laying and remove infested material.
• Allium leaf miner: larvae mine leaves and damage stems. Use insect mesh during local adult flight periods and remove crop debris.
• Leek rust: orange pustules develop on leaves. Space plants for airflow, avoid excessive nitrogen and remove heavily affected foliage.
• Allium white rot: leaves yellow and the base develops white fungal growth, sometimes with black resting bodies. Remove affected plants and do not move contaminated soil; avoid growing alliums in that ground because the fungus can persist for many years.

All parts, raw or cooked, are toxic to cats, dogs and horses and can damage red blood cells, causing potentially serious anaemia. Leeks are edible for people and are not known to be toxic in normal food quantities, although allergies and digestive upset can occur.

• Elephant garlic (Allium ampeloprasum Elephant Garlic Group)

  Has similarly broad, flat leaves but develops a large underground bulb divided into cloves; ordinary leeks form an elongated false stem without a large cloved bulb.

• Welsh onion (Allium fistulosum)

  Has hollow, tubular leaves rather than the flat, folded leaves of a leek and commonly forms clumps.

• Garlic (Allium sativum)

  Usually has narrower flat leaves and produces a distinct bulb of cloves with a strong garlic smell.

The epithet ampeloprasum comes from Greek words meaning 'vineyard leek', while 'leek' comes from the Old English leac, a name used for onion-like plants.

Propagation. Usually grown from seed, started under cover or sown into a prepared seedbed and transplanted. For seed saving, retain healthy plants through their second year; different leek varieties can cross-pollinate.

Accepted botanical name

Allium ampeloprasum

In the US and Canada

Introduced in the lower 48 states.

Native range

Albania, Algeria, Baleares, Bulgaria, Cyprus, East Aegean Is., Egypt, Ethiopia, France, Greece, Iran and Iraq.

Measured

Average height 74 cm.

Sources: GBIF (CC BY 4.0), USDA PLANTS and Trefle (CC BY 4.0). The care and design notes are LandscapeGPT's own.