Zone 4 · Alliums Growing Guide

When to Plant Leek
in Zone 4

Long-season allium with mild, sweet flavour. Start very early indoors. Blanch by hilling soil up the stems for white shafts.

Plant outdoors
May 1 – May 20
Start indoors
Feb 10 – Feb 25
Last Frost
~May 1
Days to harvest
100–120 days
Difficulty
Medium
Plant now — Zone 4
Harvest window: Sep – Oct

Planting Calendar

In Zone 4, Leek should be planted outdoors May 1 – May 20, after the average last frost date of approximately May 1. Start seeds indoors around Feb 10 – Feb 25 for a head start.

Frost-hardy — harvest into November.

Care Guide

Sunlight
Full sun · 6–8 hrs/day
Watering
Regular
Spacing
6–9 inches
Soil
Fertile, well-draining, rich
Days to maturity
100–120 days
Soil pH
6.0–7.0
plant tip · Zone 4

Frost-hardy — harvest into November.

Feeding Schedule

How often
monthly
Feed type
high nitrogen
Key timing
throughout growing season

Heavy nitrogen feeder for long, thick stems. Feed monthly throughout the season.

Companion Planting for Leek

What you plant next to leek makes a real difference — some plants actively help, others compete or attract pests.

Grows well with
  • Carrots
  • Celery
  • Brassicas
Keep away from
  • Beans
  • Peas

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Common questions

In Zone 4, start leek seeds indoors around Feb 10 – Feb 25, then transplant outdoors May 1 – May 20 after your last frost around May 1. Frost-hardy — harvest into November.
Zone 4 has an average last spring frost of approximately May 1 and a first fall frost around Oct 1. These dates vary by specific location — use your ZIP code in the plant app for precision based on the nearest NOAA weather station.
Good companion crops for leek include Carrots, Celery, Brassicas. Avoid planting near Beans, Peas, which can compete for nutrients or attract pests.
Leek typically takes 100–120 days from transplant or direct sow to harvest in Zone 4. Expected harvest window: Sep – Oct.

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Leek in other zones
Crop Guides