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When to Plant Watermelon in Cimarron County, OK

Watermelon is a sprawling vine crop that produces sweet, juicy fruits in hot weather. Varieties range from personal-sized icebox types to 50-pound 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 Watermelon 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: Mar 10 Transplant: Apr 28 🍅 Harvest: Jul 7 – Aug 25
Recommended (50%) ✓ Fits season (49 days to spare)
Start indoors: Mar 15 Transplant: May 3 🍅 Harvest: Jul 12 – Aug 30
Safe Start (90%) ✓ Fits season (49 days to spare)
Start indoors: Mar 29 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.

Soil Compatibility in Cimarron County

How your county's soil matches Watermelon's growing requirements.

Soil pH

Your soil pH (6.5โ€“7.4) is within Watermelon's preferred range (6.0โ€“7.5).

Soil Texture

The loam soil in Cimarron County is excellent for Watermelon โ€” good drainage, moisture retention, and nutrient holding capacity.

Drainage

Drainage is adequate for Watermelon.

Organic Matter

Organic matter is moderate (3.5%). Annual compost additions will help Watermelon.

How to Plant Watermelon

1"
Planting Depth
30"
Between Plants
42"
Between Rows

Succession Planting Watermelon

3
successive plantings in your 182-day season

Sow every 8 weeks. Last sowing by Jul 10 to harvest before frost.

Plant Water Budget

Plant needs
1.5″/week
Rainfall provides
0.7″/week
You supply
1.6″/week
Watering frequency 2-3 times/week
Season total 2,512 gal / 100 sq ft
Drought risk

Water stress score is 8/10 โ€” consider drought-tolerant varieties and mulching

Watermelon needs ~1,424 GDD — county provides 3,048 GDD Excellent fit

Watermelon Planting Timeline โ€” Cimarron County, OK

Watermelon Planting Calendar

Activity When Date Range
Start Indoors March 15 Mar 15 โ€“ Mar 29
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 30" apart ยท Rows 42" apart

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
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

โ˜€๏ธ Sun

Full Sun (6-8+ hours)

๐Ÿ’ง Water

1.5"/week ยท 2-3 times/week

๐Ÿ“… Days to Maturity

70โ€“100 days

๐Ÿงช Soil pH

Needs 6โ€“7.5 ยท Your soil: ideal

๐Ÿ—บ๏ธ USDA Zone

Zone 6b

๐Ÿ“† Growing Season

182 days in Cimarron County

Growing Tips for Watermelon in Cimarron County

Direct sow Watermelon outdoors after April 19 in Cimarron County when soil has warmed and frost danger has passed.

Common pests for Watermelon in this region include squash vine borer and cucumber beetles. Use row covers early in the season and inspect plants weekly.

General growing tips

Start seeds indoors 3-4 weeks early or direct sow after soil is warm. Plant on mounds with plenty of space. Check ripeness by looking for a yellow ground spot and dull thump when tapped.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Level Up Your Garden

Frequently Asked Questions

When should I plant Watermelon in Cimarron County, OK?

Cimarron County is in Zone 6b with an average last frost of April 19. Plan your Watermelon 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.

๐ŸŒฑ

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.

Get Your Free Garden Planner →

Free download. Plan your entire garden season in minutes.

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.