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When to Plant Sunflower in Seward County, NE

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.

Seward County, Nebraska is in USDA Zone 5a. The average last spring frost is April 21 and the first fall frost is October 13, giving you a growing season of approximately 175 days.

At an elevation of 527 feet, Seward County receives approximately 24.2 inches of rainfall annually with predominantly loam soil. Summer highs average 84ยฐF, so choose short-season varieties of Sunflower to ensure they mature before fall.

Seward County, NE (Zone 5a) Moderate season
175 days
Last Spring Frost April 21
175 growing days
First Fall Frost October 13

Seward County Soil Profile

Soil Type

Loam

Soil pH

6.4-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (44 days to spare)
Start indoors: Feb 19 Transplant: Apr 30 🍅 Harvest: Jul 9 – Aug 27
Recommended (50%) ✓ Fits season (42 days to spare)
Start indoors: Feb 24 Transplant: May 5 🍅 Harvest: Jul 14 – Sep 1
Safe Start (90%) ✓ Fits season (45 days to spare)
Start indoors: Mar 7 Transplant: May 16 🍅 Harvest: Jul 25 – 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.

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
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

Sunflower needs ~1,105 GDD — county provides 2,275 GDD Excellent fit

Sunflower Planting Timeline โ€” Seward County, NE

Sunflower Planting Calendar

Activity When Date Range
Start Indoors February 24 Feb 24 โ€“ Mar 10
Transplant Outdoors May 5 May 5 โ€“ May 19
Direct Sow April 28 Apr 28 โ€“ May 19
Harvest July 14 Jul 14 โ€“ Sep 1

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

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Low โ€” drought tolerant

Days to Maturity

70โ€“100 days

Soil pH

6 โ€“ 7.5

USDA Zone

Zone 5a

Growing Season

175 days

Growing Tips for Seward County

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

Level Up Your Garden

Frequently Asked Questions

When should I plant Sunflower in Seward County, NE?

Seward County is in Zone 5a with an average last frost of April 21. Plan your Sunflower planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Seward County, NE?

Seward County, Nebraska is in USDA Hardiness Zone 5a. The average last spring frost is April 21 and first fall frost is October 13.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Seward County gardeners in Zone 5a organize planting dates, track what's growing, and never miss a planting window.

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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 Seward County, NE. Local conditions may vary. Last updated: April 2026.