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When to Plant Leeks in Pierce County, ND

Pierce County, North Dakota Zone 3b May

May to-do list for Pierce County, North Dakota

A quick May briefing for Pierce County, North Dakota gardeners — what's urgent, what's next, and what can wait.

Avg. last frost May 17
Avg. first frost September 22
Soil temp (4") 49°F
Watering Moderate
Pest pressure Low
Daylight 15 hrs
  1. Time to transplant leeks

    Harden off for 7 days — a little more sun each day — before planting. That's the difference between a seedling that thrives and one that stalls.

  2. Scatter leeks into prepared beds

    Sow every 2 weeks for a continuous harvest. A single big planting means a single big glut.

June will be here before you know it — start on
  • Starting indoors: leeks
  • Fall sowing: leeks

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Leeks are a mild, sweet allium that produces long white shanks. They are more refined than onions and are a key ingredient in soups, stews, and gratins.

Pierce County, North Dakota is in USDA Zone 3b. The average last spring frost is May 17 and the first fall frost is September 22, giving you a growing season of approximately 128 days.

At an elevation of 874 feet, Pierce County receives approximately 28.5 inches of rainfall annually with predominantly loam soil. Summer highs average 78°F, so choose short-season varieties of Leeks to ensure they mature before fall.

Pierce County, ND (Zone 3b) Short season
128 days
Last Spring Frost May 17
128 growing days
First Fall Frost September 22

Pierce County Soil Profile

Soil Type

Loam

Soil pH

6.7-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (5 days to spare)
Start indoors: Mar 30 Transplant: May 11 🍅 Harvest: Aug 10 – Sep 14
Recommended (50%) ✓ Fits season (2 days to spare)
Start indoors: Apr 5 Transplant: May 17 🍅 Harvest: Aug 16 – Sep 20
Safe Start (90%) ✓ Fits season (5 days to spare)
Start indoors: Apr 16 Transplant: May 28 🍅 Harvest: Aug 27 – Oct 1

Percentages indicate frost risk at transplant. The 70% safe window means there is a 30% chance of frost after transplant — suitable for cold-hardy crops or gardeners with frost protection. The 90% safe window is best for tender plants.

Soil Compatibility in Pierce County

How your county's soil matches Leeks's growing requirements.

Soil pH

Your soil pH (6.7–7.8) is more alkaline than Leeks prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

The loam soil in Pierce County is excellent for Leeks — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is excellent (4.0%) — Leeks will thrive.

How to Plant Leeks

1"
Planting Depth
15"
Between Plants
24"
Between Rows

Fall planting: Sow 12 weeks before your first frost date for a fall harvest.

Plant Water Budget

Plant needs
0.8″/week
Rainfall provides
0.9″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Leeks

Leeks needs approximately 0.8 inches of water per week (3.5" per month). Here's how your county's rainfall compares month by month.

Month Leeks Needs Rainfall You Supplement Action
Jan 0.8" 0" ❄️ Dormant
Feb 1" 0" ❄️ Dormant
Mar 2" 0" ❄️ Dormant
Apr 3.2" 0" ❄️ Dormant
May 3.5" 3.7" 0" ✅ Rainfall sufficient
Jun 3.5" 4.7" 0" ✅ Rainfall sufficient
Jul 3.5" 4" 0" ✅ Rainfall sufficient
Aug 3.5" 3.1" 0.4" 💧 Light watering
Sep 3.5" 2.9" 0.6" 💧 Light watering
Oct 1.6" 0" ❄️ Dormant
Nov 0.8" 0" ❄️ Dormant
Dec 0.6" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Pierce County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Leeks Heat Requirements (GDD)

What are Growing Degree Days (GDD)?

Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.

Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.

Leeks needs ~1,020 GDD — county provides 1,088 GDD Good fit

Leeks Planting Timeline — Pierce County, ND

Leeks Planting Calendar

Activity When Date Range
Start Indoors April 5 Apr 5 – Apr 19
Transplant Outdoors May 17 May 17 – May 31
Direct Sow May 10 May 10 – May 31
Harvest August 16 Aug 16 – Sep 20
Fall Sowing June 30 Jun 30 – Jul 14

Plant 1" deep · 15" apart · Rows 24" apart

Month-by-Month Timeline

MonthActivities
January
February
March
April Start Indoors
May Transplant Outdoors Direct Sow
June Fall Sowing
July Fall Sowing
August Harvest
September Harvest
October
November
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.8"/week · Natural rainfall sufficient

📅 Days to Maturity

90–150 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 3b

📆 Growing Season

128 days in Pierce County

Growing Tips for Leeks in Pierce County

Direct sow Leeks outdoors after May 17 in Pierce County when soil has warmed and frost danger has passed.

Your 128.0-day growing season in Pierce County is tight for Leeks (90.0-150.0 days to maturity). Start indoors and choose early-maturing varieties.

Common pests for Leeks in this region include onion maggots and thrips. Use row covers early in the season and inspect plants weekly.

General growing tips

Start seeds indoors 10-12 weeks before last frost. Transplant into trenches and hill soil around stems as they grow to increase the white portion. Harvest as needed.

Companion Planting

Good Companions

Avoid Planting Near

  • Peas
  • Green Beans

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Leeks in Pierce County, ND?

Pierce County is in Zone 3b with an average last frost of May 17. Plan your Leeks planting based on this frost date — see the calendar above for exact timing.

What planting zone is Pierce County, ND?

Pierce County, North Dakota is in USDA Hardiness Zone 3b. The average last spring frost is May 17 and first fall frost is September 22.

🌱

Your Pierce County Garden Planner — Free

A 24-page printable planner built for Pierce County (Zone 3b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

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Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Pierce County, ND. Local conditions may vary. Last updated: May 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.