Leek
Autumn Leek, Summer Leek, King Richard, Musselburgh
Start indoors 8–10 weeks before last frost. Transplant into 6" deep trenches; gradually fill in soil (hilling) as plants grow to blanch and lengthen the white shank. Hardy — survives frost and can overwinter in zones 6–9 for spring harvest. Slow growing but largely trouble-free. Thin to 6" apart.
- Germination
- 7–14 days
- Soil temperature
- 10–24 °C
- Harvest after planting
- 100–130 days
- Spacing
- 15–25 cm
When to plant leek
Start seeds indoors 8–10 weeks before your last spring frost, and plant out within 2 weeks after it.
Dashed line: typical last spring frost in zone 7 (Apr 5). Zone dates are averages; most of the UK is zone 8–9, central Europe 6–7 and the Baltics and Scandinavia 4–6. In the app, Tomatograph uses your garden's own frost dates.
How to grow leek
- 1
Sow indoors
Sow 6 mm deep 8–10 weeks before the last frost. Seedlings appear in 7–14 days.
- 2
Plant deep
After the last frost, drop seedlings into holes or a trench 15 cm deep and 15 cm apart, then water them in without filling the holes.
- 3
Earth up
Draw soil up around the stems as they grow to blanch and lengthen the white part.
- 4
Harvest
Lift from 100–130 days after planting. Leeks are hardy and can stand in the ground through winter in mild areas.
Growing conditions
Light
Full sun
Water
Medium water
Temperature
-5–24 °C
Frost tolerance
Frost-hardy — tolerates frost
Days to maturity
100–150 days
Plant spacing
15 cm
How Tomatograph watches your leek
Tomatograph checks your local forecast every morning and only speaks up when one of these applies to your garden.
- First frost within 14 daysReminder to mulch the roots before winter.
- 3 days at 35 °C or aboveHeat-wave alert while plants are flowering or fruiting: shade and water early.
- Humidity above 80% for 48 hoursCheck for rust, which thrives in those conditions.
- Within a week of maturityHarvest-window reminder based on when you planted.
Leek questions
- When should I plant leek?
- Start seeds indoors 8–10 weeks before your last spring frost, and plant out within 2 weeks after it.
- How long do leek seeds take to germinate?
- Usually 7–14 days at a soil temperature of 10–24 °C.
- How long until I can harvest leek?
- About 100–130 days after planting out, depending on variety and weather.
- How far apart should I plant leek?
- Allow 15–25 cm between plants.
- What grows well with leek?
- Good neighbours include carrot, celery, onion.
Growing guide written by Tomatograph. Planting figures from openplantdb (CC0 1.0). Zone frost dates are averages from openplantdb (CC0 1.0).