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Leek

Bulb
Long cool season
Full sun

Also known as: Allium ampeloprasum

Varieties

4 types of leek

When & where

Season
Long cool season — spring through late fall/winter
USDA zones
3–9 (many overwinter in zones 7+)
Sun
Full sun
Start indoors
10–12 weeks before last frost
Direct sow outdoors
As soon as soil can be worked, or set out transplants
Days to harvest
80–130 days from transplant

Germination

Germination time
7–14 days
Soil temperature
65–75°F (18–24°C)

Spacing & depth

Sow depth
1/4" (6 mm)
Seed spacing
Sow thickly in flats, transplant to 6 in
Mature plant spacing
6 in (15 cm)
Row spacing
12–18 in (30–45 cm)

How to plant

Start indoors in a deep flat. When pencil-thick, trim tops to 4" and drop each seedling into a 6" dibbled hole; do not backfill — water settles just enough soil around the roots. Hill soil up the shanks over the season to blanch long white stems.

Grower's tip

For the longest white shank, plant deep or trench 4–6 inches and hill as they grow. Fall/winter varieties survive frozen ground under mulch.

Soil preferences

Soil type

Loose, well-drained soil — bulbs rot in wet feet.

pH range

6.0–7.0

Amendments

Compost + bone meal or rock phosphate worked into the planting hole.

Watering

Frequency

Water in at planting, then only during active growth. Let bulbs go dry during dormancy.

Method

Deep watering at the base. Avoid overhead watering after leaves die back.

Over vs. under

Overwatered: soft, mushy bulbs at harvest; basal plate rot. Underwatered: small bulbs, thin necks.

Top-water or bottom-water?

Prefers top-watering — Top-water at the soil surface — keep the necks and crowns as dry as possible to prevent basal rot.

Temperature tolerance

Ideal daytime air temp

60–75°F (15–24°C) during growth

Ideal nighttime air temp

40–60°F (4–15°C)

Frost sensitivity

Hardneck garlic, shallots, and daffodils need a cold winter to bulb properly. Tender bulbs (dahlia, gladiolus) must be lifted in cold zones.

Container growing

Container-suitable?

Yes — great in containers

Recommended pot size

8+ in deep, wide enough to space bulbs 2–3× their diameter

Notes

Deep pot for tulips and daffodils; shallow bowls for crocus.

Detailed harvesting

For garlic and onion: dig when the bottom 3 leaves brown and top leaves still stand. Loosen with a fork, don't yank. Cure whole plants 2–3 weeks in a warm, airy, shaded spot.

Post-harvest storage & preservation

After curing, trim tops and roots. Store hardneck garlic 4–6 months, softneck 8+ months in a cool (50–60°F), dry, dark spot with airflow. Never in the fridge.

Culinary, medicinal & other uses

Culinary staple (allium bulbs), cut flowers (tulip, daffodil, lily), forced blooms indoors, or perennial garden color.

Medicinal or traditional uses are shared for interest only — this is not medical advice. Consult a qualified professional before using any plant medicinally.

Seed saving

Pollination

Propagate by offset bulblets, not seed — bulbs mature much faster from a clove/bulb than from seed.

Isolation needs

Not applicable when replanting clones. Cross-pollinated seed rarely comes true.

How to save

Save the biggest, firmest bulbs each year and replant. Over generations you build a locally-adapted strain.

Your zone's planting calendar

Pick your USDA hardiness zone and we'll estimate the key dates for leek in your area. These are regional averages — always check your own last-frost forecast before sowing.

From your kitchen — grow leek from what you already have

Bulbs propagate from offsets and bulblets, not seed. Every year the parent bulb makes more of itself underground.

  1. 1At harvest or dormancy, lift the clump and gently split off the smaller side-bulbs.
  2. 2Cure the bulbs 2–3 weeks in a warm airy spot until the necks are dry.
  3. 3Save the biggest for eating and the medium-sized ones for replanting.
  4. 4Replant at the recommended time for this crop, point-up, at the depth listed above.

Storage: Bulb strains adapt to your garden year over year — the older your stock, the better it grows.

My Leek notes

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