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When to Plant Sunflower in Cimarron County, OK

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.

Cimarron County, Oklahoma is in USDA Zone 6b. The average last spring frost is April 19 and the first fall frost is October 18, giving you a growing season of approximately 182 days.

At an elevation of 1,132 feet, Cimarron County receives approximately 28.5 inches of rainfall annually with predominantly loam soil. Summer highs average 89ยฐF, providing good warmth for Sunflower during the growing season.

Cimarron County, OK (Zone 6b) Moderate season
182 days
Last Spring Frost April 19
182 growing days
First Fall Frost October 18

Cimarron County Soil Profile

Soil Type

Loam

Soil pH

6.5-7.4

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (48 days to spare)
Start indoors: Feb 17 Transplant: Apr 28 🍅 Harvest: Jul 7 – Aug 25
Recommended (50%) ✓ Fits season (49 days to spare)
Start indoors: Feb 22 Transplant: May 3 🍅 Harvest: Jul 12 – Aug 30
Safe Start (90%) ✓ Fits season (49 days to spare)
Start indoors: Mar 8 Transplant: May 17 🍅 Harvest: Jul 26 – Sep 13

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
0.7″/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 ~1,424 GDD — county provides 3,048 GDD Excellent fit

Sunflower Planting Timeline โ€” Cimarron County, OK

Sunflower Planting Calendar

Activity When Date Range
Start Indoors February 22 Feb 22 โ€“ Mar 8
Transplant Outdoors May 3 May 3 โ€“ May 17
Direct Sow April 26 Apr 26 โ€“ May 17
Harvest July 12 Jul 12 โ€“ Aug 30

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

Month-by-Month Timeline

MonthActivities
January โ€”
February Start Indoors
March Start Indoors
April Direct Sow
May Transplant Outdoors Direct Sow
June โ€”
July Harvest
August Harvest
September โ€”
October โ€”
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 6b

Growing Season

182 days

Growing Tips for Cimarron 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 Cimarron County, OK?

Cimarron County is in Zone 6b with an average last frost of April 19. Plan your Sunflower planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Cimarron County, OK?

Cimarron County, Oklahoma is in USDA Hardiness Zone 6b. The average last spring frost is April 19 and first fall frost is October 18.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Cimarron County gardeners in Zone 6b 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 Cimarron County, OK. Local conditions may vary. Last updated: April 2026.