When to Plant Sunflower in Rich County, UT
Sunflower (Helianthus annuus) is a fast-growing North American native annual famous for its towering stems and brilliant yellow heads. It thrives in full sun and heat, producing large, pollen-rich blooms that attract bees, butterflies, and seed-eating birds. Varieties range from 18-inch dwarfs to 12-foot giants and nearly every color except blue.
Rich County, Utah is in USDA Zone 5a. 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
Monthly Watering Guide for Sunflower
Sunflower needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Sunflower Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.3" | 0" | ❄️ Dormant |
| Feb | — | 1.1" | 0" | ❄️ Dormant |
| Mar | — | 1.7" | 0" | ❄️ Dormant |
| Apr | — | 2" | 0" | ❄️ Dormant |
| May | 4.3" | 1.9" | 2.4" | 🚿 Regular watering |
| Jun | 4.3" | 1.4" | 2.9" | 🚿 Regular watering |
| Jul | 4.3" | 1.7" | 2.6" | 🚿 Regular watering |
| Aug | 4.3" | 1.7" | 2.6" | 🚿 Regular watering |
| Sep | 4.3" | 1.4" | 2.9" | 🚿 Regular watering |
| Oct | — | 1.6" | 0" | ❄️ Dormant |
| Nov | — | 1.1" | 0" | ❄️ Dormant |
| Dec | — | 1.1" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Sep in Rich County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Sunflower Planting Timeline — Rich County, UT
Sunflower Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | May 10 | May 10 – May 24 |
| Transplant Outdoors | June 7 | Jun 7 – Jun 21 |
| Direct Sow | June 7 | Jun 7 – Jun 28 |
| Bloom | August 30 | Aug 30 – Nov 8 |
Plant 1" deep · 18" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | Start Indoors |
| June | Transplant Outdoors Direct Sow |
| July | — |
| August | Bloom |
| September | Bloom |
| October | Bloom |
| November | Bloom |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
Low — drought tolerant
📅 Days to Maturity
70–100 days
🧪 Soil pH
Needs 6–7.5 · Your soil: N/A
🗺️ USDA Zone
Zone 5a
📆 Growing Season
107 days in Rich County
Growing Tips for Rich County
Direct-sow 1 inch deep after last frost; germination takes 7-14 days at 65-75°F soil. Sunflowers dislike root disturbance so direct sowing is strongly preferred over transplanting. Plant in succession every 2 weeks for extended bloom. Stake tall varieties. Avoid overwatering — they tolerate drought once established. Birds will self-deadhead seed heads; leave them up through fall for wildlife.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Sunflower in Other Locations
Frequently Asked Questions
When should I plant Sunflower in Rich County, UT?
Rich County is in Zone 5a 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 5a. The average last spring frost is May 31 and first fall frost is September 15.
Your Rich County Garden Planner — Free
A 22-page printable planner built for Rich County (Zone 5a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.