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When to Plant Sunflower in Morgan County, UT

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.

Morgan County, Utah is in USDA Zone 5b. The average last spring frost is June 17 and the first fall frost is August 31, giving you a growing season of approximately 75 days.

At an elevation of 6,439 feet, Morgan County receives approximately 14.4 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. With low rainfall, drip irrigation is essential for growing Sunflower successfully. Mulch heavily to conserve soil moisture.

Morgan County, UT (Zone 5b) Very short season
75 days
Last Spring Frost June 17
75 growing days
First Fall Frost August 31

Morgan County Soil Profile

Soil Type

Loam

Soil pH

6.5-8.1

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 15 Transplant: Jun 24 🍅 Harvest: Sep 2 – Oct 21
Recommended (50%) ✗ May not fit
Start indoors: Apr 22 Transplant: Jul 1 🍅 Harvest: Sep 9 – Oct 28
Safe Start (90%) ✗ May not fit
Start indoors: Apr 29 Transplant: Jul 8 🍅 Harvest: Sep 16 – Nov 4

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
0.8″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

Water stress score is 8/10 โ€” consider drought-tolerant varieties and mulching

Sunflower needs ~1,105 GDD — county provides 975 GDD May not mature

Sunflower Planting Timeline โ€” Morgan County, UT

Sunflower Planting Calendar

Activity When Date Range
Start Indoors April 22 Apr 22 โ€“ May 6
Transplant Outdoors July 1 Jul 1 โ€“ Jul 15
Direct Sow June 24 Jun 24 โ€“ Jul 15
Harvest September 9 Sep 9 โ€“ Oct 28

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

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April Start Indoors
May Start Indoors
June Direct Sow
July Transplant Outdoors Direct Sow
August โ€”
September Harvest
October Harvest
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 5b

Growing Season

75 days

Growing Tips for Morgan 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 Morgan County, UT?

Morgan County is in Zone 5b with an average last frost of June 17. Plan your Sunflower planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Morgan County, UT?

Morgan County, Utah is in USDA Hardiness Zone 5b. The average last spring frost is June 17 and first fall frost is August 31.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Morgan County gardeners in Zone 5b 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 Morgan County, UT. Local conditions may vary. Last updated: April 2026.