When to Plant Watermelon in Spokane 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.
Spokane County, Washington is in USDA Zone 6a. The average last spring frost is May 11 and the first fall frost is September 27, giving you a growing season of approximately 139 days.
At an elevation of 1,645 feet, Spokane County receives approximately 20.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 91°F, providing good warmth for Watermelon during the growing season.
Spokane County Soil Profile
Soil Type
Silt Loam
Soil pH
5.5-6.2
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.
Soil Compatibility in Spokane County
How your county's soil matches Watermelon's growing requirements.
Soil pH
Your soil pH (5.5–6.2) is more acidic than Watermelon prefers (6.0–7.5). Add garden lime to raise pH.
Soil Texture
The silt loam soil in Spokane County is excellent for Watermelon — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (5.4%) — Watermelon will thrive.
How to Plant Watermelon
Succession Planting Watermelon
Sow every 8 weeks. Last sowing by Jun 19 to harvest before frost.
Plant Water Budget
Watermelon Planting Timeline — Spokane County, WA
Watermelon Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 6 | Apr 6 – Apr 20 |
| Transplant Outdoors | May 25 | May 25 – Jun 8 |
| Direct Sow | May 18 | May 18 – Jun 8 |
| Harvest | August 3 | Aug 3 – Sep 21 |
Plant 1" deep · 30" apart · Rows 42" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Start Indoors |
| May | Transplant Outdoors Direct Sow |
| June | Transplant Outdoors Direct Sow |
| July | — |
| August | Harvest |
| September | Harvest |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1.5"/week · 2-3 times/week
📅 Days to Maturity
70–100 days
🧪 Soil pH
Needs 6–7.5 · Your soil: too_acidic
🗺️ USDA Zone
Zone 6a
📆 Growing Season
139 days in Spokane County
Growing Tips for Watermelon in Spokane County
Direct sow Watermelon outdoors after May 11 in Spokane 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.
Spokane County receives only 20" of rain annually. Watermelon needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
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.
Recommended Watermelon Varieties for Spokane County
Compact, early melons for shorter seasons
Companion Planting
Good Companions
Avoid Planting Near
Level Up Your Garden
Watermelon in Other Locations
Frequently Asked Questions
When should I plant Watermelon in Spokane County, WA?
Spokane County is in Zone 6a with an average last frost of May 11. Plan your Watermelon planting based on this frost date — see the calendar above for exact timing.
What planting zone is Spokane County, WA?
Spokane County, Washington is in USDA Hardiness Zone 6a. The average last spring frost is May 11 and first fall frost is September 27.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Spokane County gardeners in Zone 6a organize planting dates, track what's growing, and never miss a planting window.
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