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When to Plant Sweet Corn in Pembina County, ND

Pembina County, North Dakota Zone 4a May

What to do in May

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

Avg. last frost May 15
Avg. first frost September 28
Soil temp (4") 49°F
Watering Moderate
Pest pressure Low
Daylight 15 hrs
  1. Outdoor sowing time: sweet corn

    Thin ruthlessly once seedlings are up. Crowded roots mean smaller crops from every plant.

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Sweet corn is bred for high sugar content in its kernels, which convert to starch rapidly after harvest. Modern supersweet varieties hold their sweetness longer.

Pembina County, North Dakota is in USDA Zone 4a. The average last spring frost is May 15 and the first fall frost is September 28, giving you a growing season of approximately 136 days.

At an elevation of 958 feet, Pembina County receives approximately 26.5 inches of rainfall annually with predominantly loam soil. Summer highs average 79°F, so choose short-season varieties of Sweet Corn to ensure they mature before fall.

Pembina County, ND (Zone 4a) Short season
136 days
Last Spring Frost May 15
136 growing days
First Fall Frost September 28

Pembina County Soil Profile

Soil Type

Loam

Soil pH

6.6-7.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (29 days to spare)
Transplant: May 11 🍅 Harvest: Jul 13 – Aug 24
Recommended (50%) ✓ Fits season (31 days to spare)
Transplant: May 15 🍅 Harvest: Jul 17 – Aug 28
Safe Start (90%) ✓ Fits season (30 days to spare)
Transplant: May 30 🍅 Harvest: Aug 1 – Sep 12

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 Pembina County

How your county's soil matches Sweet Corn's growing requirements.

Soil pH

Your soil pH (6.6–7.3) overlaps with Sweet Corn's range (6.0–7.0), though not a perfect match.

Soil Texture

The loam soil in Pembina County is excellent for Sweet Corn — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is excellent (4.2%) — Sweet Corn will thrive.

How to Plant Sweet Corn

1"
Planting Depth
12"
Between Plants
36"
Between Rows

Succession Planting Sweet Corn

2
successive plantings in your 136-day season

Sow every 6.9 weeks. Last sowing by Jun 30 to harvest before frost.

Plant Water Budget

Plant needs
1.5″/week
Rainfall provides
0.8″/week
You supply
0.7″/week
Watering frequency 1-2 times/week
Season total 825 gal / 100 sq ft

Monthly Watering Guide for Sweet Corn

Sweet Corn needs approximately 1.5 inches of water per week (6.5" per month). Here's how your county's rainfall compares month by month.

Month Sweet Corn Needs Rainfall You Supplement Action
Jan 0.7" 0" ❄️ Dormant
Feb 1" 0" ❄️ Dormant
Mar 1.7" 0" ❄️ Dormant
Apr 2.6" 0" ❄️ Dormant
May 6.5" 3.6" 2.9" 💧 Light watering
Jun 6.5" 4.7" 1.8" 💧 Light watering
Jul 6.5" 3.2" 3.3" 🚿 Regular watering
Aug 6.5" 3.4" 3.1" 💧 Light watering
Sep 6.5" 2.7" 3.8" 🚿 Regular watering
Oct 1.4" 0" ❄️ Dormant
Nov 0.8" 0" ❄️ Dormant
Dec 0.6" 0" ❄️ Dormant

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

Sweet Corn 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.

Sweet Corn needs ~694 GDD — county provides 1,258 GDD Excellent fit

Sweet Corn Planting Timeline — Pembina County, ND

Sweet Corn Planting Calendar

Activity When Date Range
Direct Sow May 29 May 29 – Jun 19
Harvest July 31 Jul 31 – Sep 11

Plant 1" deep · 12" apart · Rows 36" apart

Month-by-Month Timeline

MonthActivities
January
February
March
April
May Direct Sow
June Direct Sow
July Harvest
August Harvest
September Harvest
October
November
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.5"/week · 1-2 times/week

📅 Days to Maturity

60–90 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 4a

📆 Growing Season

136 days in Pembina County

Growing Tips for Sweet Corn in Pembina County

Direct sow Sweet Corn outdoors after May 15 in Pembina County when soil has warmed and frost danger has passed.

Common pests for Sweet Corn in this region include corn earworm and corn borers. Use row covers early in the season and inspect plants weekly.

General growing tips

Plant in blocks of at least 4 rows for wind pollination. Direct sow after soil is warm. Isolate supersweet varieties from other corn types to prevent cross-pollination.

Companion Planting

Good Companions

Avoid Planting Near

  • Tomatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Sweet Corn in Pembina County, ND?

Pembina County is in Zone 4a with an average last frost of May 15. Plan your Sweet Corn planting based on this frost date — see the calendar above for exact timing.

What planting zone is Pembina County, ND?

Pembina County, North Dakota is in USDA Hardiness Zone 4a. The average last spring frost is May 15 and first fall frost is September 28.

🌱

Your Pembina County Garden Planner — Free

A 24-page printable planner built for Pembina 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 Pembina 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.