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When to Plant Leeks in Benson County, ND

Benson County, North Dakota Zone 4a May

What to do in May

Here's what deserves your attention in Benson County, North Dakota this month. Everything below is tailored to Zone 4a and timed around your local frost dates.

Avg. last frost May 13
Avg. first frost September 27
Soil temp (4") 51°F
Watering Low
Pest pressure Low
Daylight 15 hrs
  1. Set out leeks seedlings

    Pick a cloudy afternoon or evening to plant. Less transplant shock, and your seedlings will barely blink.

  2. Outdoor sowing time: leeks

    Mark the row. Birds and stray feet both have opinions about unmarked beds.

Coming up in June — start thinking about
  • Starting indoors: 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.

Benson County, North Dakota is in USDA Zone 4a. The average last spring frost is May 13 and the first fall frost is September 27, giving you a growing season of approximately 137 days.

At an elevation of 869 feet, Benson County receives approximately 34 inches of rainfall annually with predominantly loam soil. Summer highs average 79°F, so choose short-season varieties of Leeks to ensure they mature before fall.

Benson County, ND (Zone 4a) Short season
137 days
Last Spring Frost May 13
137 growing days
First Fall Frost September 27
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Benson County Soil Profile

Soil Type

Loam

Soil pH

6.6-7.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 26 Transplant: May 7 🍅 Harvest: Aug 6 – Oct 1
Recommended (50%) ✗ May not fit
Start indoors: Apr 1 Transplant: May 13 🍅 Harvest: Aug 12 – Oct 7
Safe Start (90%) ✗ May not fit
Start indoors: Apr 10 Transplant: May 22 🍅 Harvest: Aug 21 – Oct 16

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 Benson County

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

Soil pH

Your soil pH (6.6–7.6) is more alkaline than Leeks prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (3.3%). Annual compost additions will help Leeks.

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
1.0″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft

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 0.9" 0" ❄️ Dormant
Feb 1.2" 0" ❄️ Dormant
Mar 2.3" 0" ❄️ Dormant
Apr 3.8" 0" ❄️ Dormant
May 3.5" 5.4" 0" ✅ Rainfall sufficient
Jun 3.5" 5.2" 0" ✅ Rainfall sufficient
Jul 3.5" 3.9" 0" ✅ Rainfall sufficient
Aug 3.5" 4.1" 0" ✅ Rainfall sufficient
Sep 3.5" 3.1" 0.4" 💧 Light watering
Oct 2" 0" ❄️ Dormant
Nov 1.2" 0" ❄️ Dormant
Dec 1" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Benson 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 ~1,110 GDD — county provides 1,267 GDD Good fit

Leeks Planting Timeline — Benson County, ND

Leeks Planting Calendar

Activity When Date Range
Start Indoors April 1 Apr 1 – Apr 15
Transplant Outdoors May 13 May 13 – May 27
Direct Sow May 6 May 6 – May 27
Harvest August 12 Aug 12 – Oct 7
Fall Sowing July 5 Jul 5 – Jul 19

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
July Fall Sowing
August Harvest
September Harvest
October Harvest
November
December
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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 4a

📆 Growing Season

137 days in Benson County

Growing Tips for Leeks in Benson County

Direct sow Leeks outdoors after May 13 in Benson County when soil has warmed and frost danger has passed.

Your 137.0-day growing season in Benson 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 Benson County, ND?

Benson County is in Zone 4a with an average last frost of May 13. Plan your Leeks planting based on this frost date — see the calendar above for exact timing.

What planting zone is Benson County, ND?

Benson County, North Dakota is in USDA Hardiness Zone 4a. The average last spring frost is May 13 and first fall frost is September 27.

🌱

Your Benson County Garden Planner — Free

A 24-page printable planner built for Benson County (Zone 4a). 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 Benson 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.