Leek Allium ampeloprasum (Porrum group)
Leek (Allium ampeloprasum (Porrum group)) is a biennial vegetable in the Amaryllidaceae family. It grows 50–80 cm (20–31 in) tall and 10–20 cm (4–8 in) wide, wants full sun and moderate water, and is hardy to about -15 °C (5 °F). Space plants about 15 cm (6 in) apart.
Plan Leek in your garden →
Free. Draw your beds, then watch it grow through the year in 2D and 3D.
Leek at a glance
| Type | Biennial vegetable |
|---|---|
| Family | Amaryllidaceae |
| Mature height | 50–80 cm (20–31 in) |
| Mature spread | 10–20 cm (4–8 in) |
| Spacing | 15 cm (6 in) centre to centre |
| Sun | Full sun, at least 6 h of direct sun a day |
| Water | Moderate; drought tolerance low, waterlogging tolerance none |
| Cold hardiness | About -15 °C (5 °F) once established (roughly USDA zone 7) |
| Heat stress | Likely above about 28 °C (82 °F) |
| Flowering | about 52–60 weeks after planting, for 2–4 weeks |
| Days to maturity | About 150 days from planting |
| Wind tolerance | Moderate |
| Pollinator value | Low |
| Edible | Yes: stems, leaves |
| Common in gardens of | 🇬🇧 United Kingdom, 🇫🇷 France, 🇩🇪 Germany, 🇺🇸 United States, 🇳🇱 Netherlands, 🇮🇪 Ireland |
Is Leek toxic?
- People: not known to be toxic
- Cats: moderately toxic
- Dogs: moderately toxic
- Parts: all parts
Leeks are toxic to cats and dogs, as with other alliums.
If a child or pet may have eaten part of a plant, call a poison centre or vet straight away.
Companion planting: what to grow with Leek
No well-documented helpful pairing. Group it with plants that like full sun and moderate water.
Keep apart or take care
- caution With Legumes (pea family): Onions, garlic and leeks are said to stunt beans and peas (allium root exudates may reduce nodulation). Traditional companion-planting advice; controlled trials are few, so treat it as a soft preference. Evidence D
- caution With Legumes (pea family): Beans and peas are traditionally kept away from onions, garlic and leeks. Traditional companion-planting advice; controlled trials are few, so treat it as a soft preference. Evidence D
Shared pests and diseases
- White rot: Allium white rot survives in soil for 15+ years; never move infected soil. Evidence B
Questions about Leek
- How far apart should I plant Leek?
- About 15 cm (6 in) apart, centre to centre. A mature plant spreads 10–20 cm (4–8 in).
- Does Leek need full sun?
- Full sun: at least 6 hours of direct sun a day.
- How much water does Leek need?
- Moderate water. Drought tolerance is low and waterlogging tolerance none.
- How cold-hardy is Leek?
- It tolerates about -15 °C (5 °F) once established, roughly USDA zone 7. As a biennial it is usually planted out after the last frost and flowers in its second year.
- When does Leek flower?
- About 52–60 weeks after planting, for 2–4 weeks.
- Is Leek poisonous to cats and dogs?
- For cats it is moderately toxic; for dogs moderately toxic; for people not known to be toxic. Leeks are toxic to cats and dogs, as with other alliums.
- What grows well with Leek?
- There is no well-documented companion pairing for Leek. Group it with plants that like the same sun (full sun) and water (moderate).
Sources and evidence
Evidence grade C (C: plausible, mixed evidence).
- ASPCA Toxic and Non-Toxic Plant List, ASPCA
- FAO Irrigation and Drainage Paper 56 — Crop Evapotranspiration, FAO
- RHS Plant Finder, Royal Horticultural Society
- University extension gardening guides (general), Various land-grant university extensions
Notes and assumptions
- Typical garden-cultivar values; varieties differ.
Reference values for planning, not horticultural, veterinary or medical advice. Varieties, soils and local climates differ: check with a local nursery or extension service.
Related plants
- Onion Allium cepa
- Daffodil Narcissus pseudonarcissus
- Garlic Allium sativum
- Chives Allium schoenoprasum
- Agapanthus Agapanthus praecox
- Ornamental allium Allium giganteum
- Shallot Allium cepa var. aggregatum
- Welsh onion (scallion) Allium fistulosum