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When to Plant Sweet Corn in Rolette County, ND

Rolette County, North Dakota Zone 3b May

Your May gardening checklist

Each item below is timed to Rolette County, North Dakota's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost May 17
Avg. first frost September 22
Soil temp (4") 49°F
Watering Low
Pest pressure Low
Daylight 15 hrs
  1. Outdoor sowing time: sweet corn

    Keep the top inch of soil moist until germination — a gentle morning watering for 5–7 days does the job.

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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.

Rolette 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 998 feet, Rolette County receives approximately 31.8 inches of rainfall annually with predominantly loam soil. Summer highs average 78°F, so choose short-season varieties of Sweet Corn to ensure they mature before fall.

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

Soil Type

Loam

Soil pH

6.5-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (26 days to spare)
Transplant: May 11 🍅 Harvest: Jul 13 – Aug 24
Recommended (50%) ✓ Fits season (23 days to spare)
Transplant: May 17 🍅 Harvest: Jul 19 – Aug 30
Safe Start (90%) ✓ Fits season (26 days to spare)
Transplant: May 28 🍅 Harvest: Jul 30 – Sep 10

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 Rolette County

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

Soil pH

Your soil pH (6.5–7.8) is more alkaline than Sweet Corn prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (3.8%). Annual compost additions will help Sweet Corn.

How to Plant Sweet Corn

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

Succession Planting Sweet Corn

2
successive plantings in your 128-day season

Sow every 6.9 weeks. Last sowing by Jun 24 to harvest before frost.

Plant Water Budget

Plant needs
1.5″/week
Rainfall provides
1.0″/week
You supply
0.6″/week
Watering frequency 1-2 times/week
Season total 624 gal / 100 sq ft
Drought risk

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

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 0.8" 0" ❄️ Dormant
Feb 1.3" 0" ❄️ Dormant
Mar 2.3" 0" ❄️ Dormant
Apr 3.5" 0" ❄️ Dormant
May 6.5" 4.4" 2.1" 💧 Light watering
Jun 6.5" 5" 1.5" 💧 Light watering
Jul 6.5" 4.3" 2.2" 💧 Light watering
Aug 6.5" 3.7" 2.8" 💧 Light watering
Sep 6.5" 2.8" 3.7" 🚿 Regular watering
Oct 2.1" 0" ❄️ Dormant
Nov 0.9" 0" ❄️ Dormant
Dec 0.7" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Rolette 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 ~638 GDD — county provides 1,088 GDD Excellent fit

Sweet Corn Planting Timeline — Rolette County, ND

Sweet Corn Planting Calendar

Activity When Date Range
Direct Sow May 31 May 31 – Jun 21
Harvest August 2 Aug 2 – Sep 13

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

Month-by-Month Timeline

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

🗺️ USDA Zone

Zone 3b

📆 Growing Season

128 days in Rolette County

Growing Tips for Sweet Corn in Rolette County

Direct sow Sweet Corn outdoors after May 17 in Rolette 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 Rolette County, ND?

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

What planting zone is Rolette County, ND?

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

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Your Rolette County Garden Planner — Free

A 24-page printable planner built for Rolette 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 Rolette 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.