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When to Plant Sunflower in Barnes County, ND

Barnes County, North Dakota Zone 4a May

May to-do list for Barnes County, North Dakota

May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Barnes County, North Dakota.

Avg. last frost May 9
Avg. first frost September 29
Soil temp (4") 55°F
Watering Moderate
Pest pressure Low
Daylight 14.8 hrs
  1. Move sunflower into the garden

    Bring a watering can to the bed. Each transplant gets a drink the moment it's in the ground, not ten minutes later.

  2. Outdoor sowing time: sunflower

    Succession planting is the secret here. Put in a row now, another in 2 weeks, a third in 4.

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Sunflowers are tall, cheerful annuals grown for their edible seeds and as pollinator magnets. They come in sizes from 2-foot dwarfs to 12-foot giants.

Barnes County, North Dakota is in USDA Zone 4a. The average last spring frost is May 9 and the first fall frost is September 29, giving you a growing season of approximately 143 days.

At an elevation of 623 feet, Barnes County receives approximately 20.5 inches of rainfall annually with predominantly loam soil. Summer highs average 84°F, so choose short-season varieties of Sunflower to ensure they mature before fall.

Barnes County, ND (Zone 4a) Short season
143 days
Last Spring Frost May 9
143 growing days
First Fall Frost September 29
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Barnes County Soil Profile

Soil Type

Loam

Soil pH

6.3-7.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (6 days to spare)
Start indoors: Feb 27 Transplant: May 22 🍅 Harvest: Jul 31 – Sep 18
Recommended (50%) ✓ Fits season (3 days to spare)
Start indoors: Mar 7 Transplant: May 30 🍅 Harvest: Aug 8 – Sep 26
Safe Start (90%) ✓ Fits season (9 days to spare)
Start indoors: Mar 17 Transplant: Jun 9 🍅 Harvest: Aug 18 – Oct 6

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 Barnes County

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

Soil pH

Your soil pH (6.3–7.7) overlaps with Sunflower's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (3.7%). Annual compost additions will help Sunflower.

How to Plant Sunflower

1"
Planting Depth
18"
Between Plants
30"
Between Rows

Succession Planting Sunflower

2
successive plantings in your 143-day season

Sow every 8 weeks. Last sowing by Jun 21 to harvest before frost.

Plant Water Budget

Plant needs
0.5″/week
Rainfall provides
0.6″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft

Monthly Watering Guide for Sunflower

Sunflower needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.

Month Sunflower Needs Rainfall You Supplement Action
Jan 0.5" 0" ❄️ Dormant
Feb 0.6" 0" ❄️ Dormant
Mar 1.4" 0" ❄️ Dormant
Apr 2.1" 0" ❄️ Dormant
May 2.2" 3.2" 0" ✅ Rainfall sufficient
Jun 2.2" 2.8" 0" ✅ Rainfall sufficient
Jul 2.2" 3" 0" ✅ Rainfall sufficient
Aug 2.2" 2.6" 0" ✅ Rainfall sufficient
Sep 2.2" 1.9" 0.3" 💧 Light watering
Oct 1.1" 0" ❄️ Dormant
Nov 0.8" 0" ❄️ Dormant
Dec 0.5" 0" ❄️ Dormant

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

Sunflower 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.

Sunflower needs ~1,105 GDD — county provides 1,859 GDD Excellent fit

Sunflower Planting Timeline — Barnes County, ND

Sunflower Planting Calendar

Activity When Date Range
Start Indoors March 7 Mar 7 – Mar 21
Transplant Outdoors May 30 May 30 – Jun 13
Direct Sow May 23 May 23 – Jun 13
Harvest August 8 Aug 8 – Sep 26

Plant 1" deep · 18" apart · Rows 30" apart

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.5"/week · Natural rainfall sufficient

📅 Days to Maturity

70–100 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 4a

📆 Growing Season

143 days in Barnes County

Growing Tips for Sunflower in Barnes County

Direct sow Sunflower outdoors after May 09 in Barnes County when soil has warmed and frost danger has passed.

Common pests for Sunflower in this region include aphids and slugs. Use row covers early in the season and inspect plants weekly.

Barnes County receives only 20" of rain annually. Sunflower needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Direct sow after last frost. Stake tall varieties in windy areas. Harvest seed heads when the back turns brown and seeds are plump. Dry heads upside down.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Sunflower in Barnes County, ND?

Barnes County is in Zone 4a with an average last frost of May 9. Plan your Sunflower planting based on this frost date — see the calendar above for exact timing.

What planting zone is Barnes County, ND?

Barnes County, North Dakota is in USDA Hardiness Zone 4a. The average last spring frost is May 9 and first fall frost is September 29.

🌱

Your Barnes County Garden Planner — Free

A 24-page printable planner built for Barnes 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 Barnes 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.