When to Plant Sunflower in Salt Lake 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.
Salt Lake County, Utah is in USDA Zone 6b. The average last spring frost is May 6 and the first fall frost is October 10, giving you a growing season of approximately 157 days.
At an elevation of 4,960 feet, Salt Lake County receives approximately 12.2 inches of rainfall annually with predominantly loam soil. Summer highs average 88°F, providing good warmth for Sunflower during the growing season. With low rainfall, drip irrigation is essential for growing Sunflower successfully. Mulch heavily to conserve soil moisture.
Salt Lake County Soil Profile
Soil Type
Loam
Soil pH
6.7-8.3
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 6/10 — consider drought-tolerant varieties and mulching
Sunflower Planting Timeline — Salt Lake County, UT
Sunflower Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 11 | Mar 11 – Mar 25 |
| Transplant Outdoors | May 20 | May 20 – Jun 3 |
| Direct Sow | May 13 | May 13 – Jun 3 |
| Harvest | July 29 | Jul 29 – Sep 16 |
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 | Harvest |
| 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 6b
Growing Season
157 days
Growing Tips for Salt Lake 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 Salt Lake County, UT?
Salt Lake County is in Zone 6b with an average last frost of May 6. Plan your Sunflower planting based on this frost date — see the calendar above for exact timing.
What planting zone is Salt Lake County, UT?
Salt Lake County, Utah is in USDA Hardiness Zone 6b. The average last spring frost is May 6 and first fall frost is October 10.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Salt Lake County gardeners in Zone 6b organize planting dates, track what's growing, and never miss a planting window.
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