Vegetable · Root & Bulb
Leek
Allium ampeloprasum var. porrum
A mild, slow-growing allium grown for its long white stalk rather than a bulb. Hilling: Mounding soil up around the base of a plant's stems as it grows, most often used with potatoes to protect developing tubers from sunlight and boost yield. soil around the base as it grows blanches the stalk and keeps it tender.
At a glance
Water
Medium
24–36 fl oz/wk
Light
Full sun
8–10 hrs/day
Space
Small
6 in
To maturity
100–120 days
Edible parts: Stem
Family: Allium
Includes onion, garlic, leek, and chives. Known for pungent, sulphur-rich compounds that give the group its characteristic smell and flavour.
Harvest
Loosen soil and pull once stalks are about an inch thick; leeks are frost-hardy and can be left in the ground and harvested as needed into winter.
Growing conditions
- Temperature
- 45–75 °F
- Soil pH
- 6–7
- Soil type
- Rich, well-draining, fertile loam
- Climate
- Cool-season and quite frost-hardy; can often be left in the ground and harvested through winter.
- Growing season
- Start seed indoors in late winter and transplant in spring; matures slowly over a long season.
- Nitrogen
- Medium (≈40–80 ppm)
- Humidity
- Medium (≈40–70 %)
- Planting unit
- Seedling
- Feeding schedule
- A heavy feeder for an allium; steady feeding through the long season supports thick, well-formed stalks.
- Pest resistance
- Moderate - generally trouble-free, occasional onion thrips
- Pests
- Onion thrips: Tiny, slender insects that rasp at leaf surfaces, leaving silvery streaks and patches, favoring alliums.
- Pruning
- Hill soil or mulch up around the base of the stalk as it grows to blanch and lengthen the edible white portion.
Where it grows
- In-Ground GardenIdeal
- Raised BedIdeal
- Container / PotPossible— Needs a deep pot (12in+) to accommodate the long white stalk.
- HydroponicPossible— Can work in deep-channel NFT systems, though blanching the stalk is harder without soil.
- Vertical / TrellisNot recommended— No climbing or vining habit.
- WindowsillNot recommended— Needs more light and root depth than a windowsill offers.
Companions & antagonists
- Beneficial: Carrot — Mutual entry for the carrot/leek pest-masking pairing - see carrot's companion notes.
- Antagonistic: Green Bean — Mutual entry for the allium/legume interference - see green bean's companion notes.
Sources
- Growing Leeks in a Home Garden — University of Maryland Extension
- Growing leeks in home gardens — University of Minnesota Extension
- Incompatible garden plants — Ask Extension