Leek

Leek: plant 15 cm (6 in) apart in the row and 35 cm (14 in) between rows, 9 per square. Good neighbours: Carrot.

Key facts

Spacing in the row	15 cm (6 in)
Between rows	35 cm (14 in)
In a 30 cm (1 ft) square	9 per square
Sun	Full sun, 6–8 hours a day
Root depth	25 cm (10 in)
Height when grown	60 cm (24 in)
Crop rotation group	Roots and onions
Support	None needed

Sowing and germination

How it is started	Started in trays, sown straight into the bed
Seeds per hole	1
Plants kept after thinning	1
Seeds per metre of row	7
Sowing depth	1.5 cm (0.6 in)
Soil temperature	from 0 °C, best 18–29 °C
Days to emerge	12–18 days
Light while germinating	Light makes no difference
Before sowing	nothing needed
When to sow	Indoors 10 weeks before the last frost; outdoors before the last frost; soil at least 7 °C

From seedling to plant

After emergence	13–20 °C; take the cover off as soon as they show
Pricking out	at 2 true leaves
Takes transplanting	Easily
Hardening off	5–7 days
Life cycle	Biennial, harvested in its first year
Cold tolerance	Takes a light frost → hardy, takes hard frost
Soil	Ordinary garden soil, free draining, pH 6–7
In a pot	8 L, 25 cm (9.8 in)
Watering	Water when the soil is dry two fingers down; while bulbs form
Feeding	Moderate; at planting, while growing
Support and training	None needed; earth up, blanch by covering

Harvest and planning

Days to first harvest	110–150 days, from planting out
Ready when	The stem is thick enough
Harvest window	Picked again and again, 8–16 weeks
Typical yield	3–5 kg per m²
Botanical family	Amaryllidaceae
Watch out for	Leek moth, rust

Good neighbours

Carrot

Why, with the sources →

Plan Leek in your garden

Open the free planner, drop Leek onto a bed and see how many plants fit.

Start Planning Your Garden

Sowing and harvest

Sow indoors	Feb–Mar
Sow outdoors	May–Jun
Harvest	Sep–Dec

My dates for this crop

My country Last spring frost where I live

Give the date once and this page, the sowing calendar and the planner all follow it.

Months for a temperate climate: about a month later in the north and a month earlier in the south. Give your own last frost date for exact dates.

What to plant next to Leek →

From the same family

Plants of the Amaryllidaceae family share diseases and pests, so they follow each other in the rotation only after a break.

Sources

The values on this page marked as checked come from these sources: spacing, sowing depth, germination, soil, timing and safety notes, each against the source named here.

Alliums: growing guidelines — UC Master Gardeners of Santa Clara County for: spacing in the row; checked 2026-10-30
People Foods to Avoid Feeding Your Pets — ASPCA Animal Poison Control Center for: safety; checked 2026-10-28
Soil Temperature Conditions for Vegetable Seed Germination (GN 154, after J.F. Harrington, UC Davis) — UC Cooperative Extension, UC ANR for: soil temperature; checked 2026-10-30

More in Onion family

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