When to Plant Sunflower in Rich 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.
Rich County, Utah is in USDA Zone 4b. The average last spring frost is May 31 and the first fall frost is September 15, giving you a growing season of approximately 107 days.
At an elevation of 5,803 feet, Rich County receives approximately 18 inches of rainfall annually with predominantly loam soil. Summer highs average 81°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.
Rich County Soil Profile
Soil Type
Loam
Soil pH
6.5-8.2
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 10/10 — consider drought-tolerant varieties and mulching
Sunflower Planting Timeline — Rich County, UT
Sunflower Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 29 | Mar 29 – Apr 12 |
| Transplant Outdoors | June 21 | Jun 21 – Jul 5 |
| Direct Sow | June 14 | Jun 14 – Jul 5 |
| Harvest | August 30 | Aug 30 – Oct 18 |
Plant 1" deep · 18" apart · Rows 30" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors |
| May | — |
| June | Transplant Outdoors Direct Sow |
| July | Transplant Outdoors Direct Sow |
| August | Harvest |
| September | Harvest |
| October | Harvest |
| 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
107 days
Growing Tips for Rich 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 Rich County, UT?
Rich County is in Zone 4b with an average last frost of May 31. Plan your Sunflower planting based on this frost date — see the calendar above for exact timing.
What planting zone is Rich County, UT?
Rich County, Utah is in USDA Hardiness Zone 4b. The average last spring frost is May 31 and first fall frost is September 15.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Rich County gardeners in Zone 4b organize planting dates, track what's growing, and never miss a planting window.
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