Leek

Allium ampeloprasum

Cool‑season · frost‑tolerant · start indoors

100–140 days from seed to harvest

Ideal15 – 24 °C

Tolerates4 – 30 °C

Leek is a cool-season bulb or stem vegetable in the amaryllis family that tolerates light frost. The usual start is indoors, then transplant, and harvest is about 100–140 days from sowing (about 14 to 20 weeks).

Primary method: start indoors

Leek is usually started indoors, then moved outside when the weather suits the tolerable range.

Start seed. Sow seed indoors. Germination typically takes 7–12 days.
Grow seedlings. Keep seedlings growing indoors until they are ready to harden off. About 7 weeks (51 days)
Harden off. Gradually acclimate indoor seedlings to outdoor conditions before planting. About 7 days
Transplant. Move seedlings outside once daytime air stays inside the tolerable range. 4 – 30 °C.
Grow to harvest. About 10–12 weeks indoors before transplant (about 70 days total). 100–140 days from sowing (about 14 to 20 weeks).

Typical days from indoor sowing to harvest — not calendar dates.

Start seed
Day 0–12
7–12 days
Grow indoors
Day 12–63
51 days
Harden off
Day 63–70
7 days
Transplant
~Day 70
when days stay within 4 – 30 °C
Grow outdoors
Day 71–100
29 days
Harvest
Day 100–140
100–140 days from seed

Direct sowing

Direct sowing is not the usual method for this plant, so there is no separate direct-sow schedule here.

Care basics

Sun: full sun, at least 6 hours of direct sun.

This plant tolerates light frost.

Types and varieties

Other names: Garden leek, Common leek. Variety groups are not listed here.

Growing facts

Growing requirements for this plant. Temperatures are daytime air temperatures in °C.
Attribute	Value
Plant name	Leek
Scientific name	Allium ampeloprasum
Family	Amaryllidaceae (amaryllis family)
Time to harvest	100–140 days from sowing (about 14 to 20 weeks)
Days to germinate	7–12 days
Ideal growing temperature	15 – 24 °C
Minimum tolerable temperature	4 °C
Maximum tolerable temperature	30 °C
Start indoors	Yes, usual method
Direct sow	Not the usual method
Season type	Cool-season, tolerates light frost
Typical start method	Start indoors, then transplant
Light	full sun, 6+ hours direct sun

Glossary

Ideal temperature: The preferred daytime range for good growth.
Tolerable temperature: A wider range where the plant can still grow, less optimally.
Harden off: Gradually acclimating indoor seedlings to outdoor conditions before transplanting.
Transplant: Moving seedlings into the garden.
Days to harvest: The usual time to harvest, counted from the start point named beside the number (seed, transplant, or planting).

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