Zone 3 · Alliums Growing Guide

When to Plant Leek
in Zone 3

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

Plant outdoors
May 15 – Jun 1
Start indoors
Mar 1 – Mar 15
Last Frost
~May 15
Days to harvest
100–120 days
Difficulty
Medium
Start indoors — Zone 3
Harvest window: Sep – Oct

Planting Calendar

In Zone 3, Leek should be planted outdoors May 15 – Jun 1, after the average last frost date of approximately May 15. Start seeds indoors around Mar 1 – Mar 15 for a head start.

Start indoors 10–12 weeks early. Short-season varieties only.

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 3

Start indoors 10–12 weeks early. Short-season varieties only.

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

These guides get better when growers like you contribute. If something’s wrong or you’ve learned something worth sharing, we’d love to hear it.

What needs correcting?

What should it say?

Your zone (optional)

Thanks — we'll review this and update the guide if needed.

Your growing tip for Leek

Your name (optional)

Your zone (optional)

Tips are reviewed before publishing. Accepted tips earn you a Founding Grower badge when the plant app launches.

Thanks for contributing! We'll review your tip and be in touch before launch.

Common questions

In Zone 3, start leek seeds indoors around Mar 1 – Mar 15, then transplant outdoors May 15 – Jun 1 after your last frost around May 15. Start indoors 10–12 weeks early. Short-season varieties only.
Zone 3 has an average last spring frost of approximately May 15 and a first fall frost around Sep 15. 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 3. Expected harvest window: Sep – Oct.

Free app · iOS February 2028

Track your Leek in plant

Get a live traffic light for every crop in your garden — zone-aware planting calendar, real-time weather alerts, and a community of growers near you.

Be first to back on Kickstarter and lock in the founding price.

Leek in other zones
Crop Guides