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When to Plant Watermelon in Lincoln County, WA

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.

Lincoln County, Washington is in USDA Zone 6a. The average last spring frost is May 19 and the first fall frost is September 26, giving you a growing season of approximately 130 days.

At an elevation of 2,955 feet, Lincoln County receives approximately 21.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87ยฐF, providing good warmth for Watermelon during the growing season.

Lincoln County, WA (Zone 6a) Short season
130 days
Last Spring Frost May 19
130 growing days
First Fall Frost September 26

Lincoln County Soil Profile

Soil Type

Silt Loam

Soil pH

5.5-6.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 3 Transplant: May 22 🍅 Harvest: Jul 31 – Sep 18
Recommended (50%) ✗ May not fit
Start indoors: Apr 14 Transplant: Jun 2 🍅 Harvest: Aug 11 – Sep 29
Safe Start (90%) ✗ May not fit
Start indoors: May 12 Transplant: Jun 30 🍅 Harvest: Sep 8 – Oct 27

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
1.0″/week
Rainfall provides
0.7″/week
You supply
0.6″/week
Watering frequency 1-2 times/week
Season total 700 gal / 100 sq ft
Watermelon needs ~1,296 GDD — county provides 1,982 GDD Excellent fit

Watermelon Planting Timeline โ€” Lincoln County, WA

Watermelon Planting Calendar

Activity When Date Range
Start Indoors April 14 Apr 14 โ€“ Apr 28
Transplant Outdoors June 2 Jun 2 โ€“ Jun 16
Direct Sow May 26 May 26 โ€“ Jun 16
Harvest August 11 Aug 11 โ€“ Sep 29

Plant 1" deep ยท 30" apart ยท Rows 42" apart

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

70โ€“100 days

Soil pH

6 โ€“ 7.5

USDA Zone

Zone 6a

Growing Season

130 days

Growing Tips for Lincoln County

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 Lincoln County, WA?

Lincoln County is in Zone 6a with an average last frost of May 19. Plan your Watermelon planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Lincoln County, WA?

Lincoln County, Washington is in USDA Hardiness Zone 6a. The average last spring frost is May 19 and first fall frost is September 26.

๐ŸŒฑ

Plan Your Garden with Confidence

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