When to Plant Sunflower in Duchesne 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.
Duchesne County, Utah is in USDA Zone 4b. The average last spring frost is May 10 and the first fall frost is October 4, giving you a growing season of approximately 147 days.
At an elevation of 5,302 feet, Duchesne County receives approximately 13 inches of rainfall annually with predominantly loam soil. Summer highs average 80°F, 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.
Duchesne County Soil Profile
Soil Type
Loam
Soil pH
6.4-8.2
Drainage
Well Drained
Plant Planting Risk Windows
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
Water stress score is 8/10 — consider drought-tolerant varieties and mulching
Sunflower Planting Timeline — Duchesne County, UT
Sunflower Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 8 | Mar 8 – Mar 22 |
| Transplant Outdoors | May 31 | May 31 – Jun 14 |
| Direct Sow | May 24 | May 24 – Jun 14 |
| Harvest | August 9 | Aug 9 – Sep 27 |
Plant 1" deep · 18" apart · Rows 30" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | — |
| May | Transplant Outdoors Direct Sow |
| June | Transplant Outdoors Direct Sow |
| July | — |
| August | Harvest |
| September | Harvest |
| October | — |
| November | — |
| December | — |
Growing Conditions
Sun
Full Sun (6-8+ hours)
Water
Low — drought tolerant
Days to Maturity
70–100 days
Soil pH
6 – 7.5
USDA Zone
Zone 4b
Growing Season
147 days
Growing Tips for Duchesne 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
Level Up Your Garden
Sunflower in Other Locations
Frequently Asked Questions
When should I plant Sunflower in Duchesne County, UT?
Duchesne County is in Zone 4b with an average last frost of May 10. Plan your Sunflower planting based on this frost date — see the calendar above for exact timing.
What planting zone is Duchesne County, UT?
Duchesne County, Utah is in USDA Hardiness Zone 4b. The average last spring frost is May 10 and first fall frost is October 4.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Duchesne County gardeners in Zone 4b organize planting dates, track what's growing, and never miss a planting window.
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