When to Plant Watermelon in Lewis County, WA
This month in Lewis County, Washington
We've pulled the most time-sensitive tasks for Lewis County, Washington this May and put them front and centre. Tackle them in order.
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Plant out watermelon
Harden off for 7 days — a little more sun each day — before planting. That's the difference between a seedling that thrives and one that stalls.
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Sow watermelon where they'll grow
Thin ruthlessly once seedlings are up. Crowded roots mean smaller crops from every plant.
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Start watermelon indoors
These need a head start before your last frost (April 25). Sow into cells now so you're ready to transplant in a few weeks.
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.
Lewis County, Washington is in USDA Zone 8a. The average last spring frost is April 25 and the first fall frost is October 24, giving you a growing season of approximately 182 days.
At an elevation of 327 feet, Lewis County receives approximately 37.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86°F, providing good warmth for Watermelon during the growing season.
Lewis County Soil Profile
Soil Type
Silt Loam
Soil pH
5.6-6.2
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 Lewis County
How your county's soil matches Watermelon's growing requirements.
Soil pH
Your soil pH (5.6–6.2) is more acidic than Watermelon prefers (6.0–7.5). Add garden lime to raise pH.
Soil Texture
The silt loam soil in Lewis County is excellent for Watermelon — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (5.3%) — Watermelon will thrive.
How to Plant Watermelon
Succession Planting Watermelon
Sow every 8 weeks. Last sowing by Jul 16 to harvest before frost.
Plant Water Budget
Monthly Watering Guide for Watermelon
Watermelon needs approximately 1.5 inches of water per week (6.5" per month). Here's how your county's rainfall compares month by month.
| Month | Watermelon Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 5.6" | 0" | ❄️ Dormant |
| Feb | — | 3.6" | 0" | ❄️ Dormant |
| Mar | — | 4.1" | 0" | ❄️ Dormant |
| Apr | 6.5" | 2.8" | 3.7" | 🚿 Regular watering |
| May | 6.5" | 2" | 4.5" | 🚿 Regular watering |
| Jun | 6.5" | 1.3" | 5.2" | 🚿 Regular watering |
| Jul | 6.5" | 0.6" | 5.9" | 🚿 Regular watering |
| Aug | 6.5" | 0.6" | 5.9" | 🚿 Regular watering |
| Sep | 6.5" | 1.4" | 5.1" | 🚿 Regular watering |
| Oct | 6.5" | 3.4" | 3.1" | 💧 Light watering |
| Nov | — | 6.3" | 0" | ❄️ Dormant |
| Dec | — | 5.7" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Lewis County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Watermelon Heat Requirements (GDD)
What are Growing Degree Days (GDD)?
Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.
Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.
Watermelon Planting Timeline — Lewis County, WA
Watermelon Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 28 | Mar 28 – Apr 11 |
| Transplant Outdoors | May 9 | May 9 – May 23 |
| Direct Sow | May 2 | May 2 – May 23 |
| Harvest | July 18 | Jul 18 – Sep 5 |
Plant 1" deep · 30" apart · Rows 42" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors |
| May | Transplant Outdoors Direct Sow |
| June | — |
| July | Harvest |
| August | Harvest |
| September | Harvest |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1.5"/week · 1-2 times/week
📅 Days to Maturity
70–100 days
🧪 Soil pH
Needs 6–7.5 · Your soil: too_acidic
🗺️ USDA Zone
Zone 8a
📆 Growing Season
182 days in Lewis County
Growing Tips for Watermelon in Lewis County
Direct sow Watermelon outdoors after April 25 in Lewis 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
Check more plant combinations with our Companion Planting Checker →
Watermelon in Other Locations
Frequently Asked Questions
When should I plant Watermelon in Lewis County, WA?
Lewis County is in Zone 8a with an average last frost of April 25. Plan your Watermelon planting based on this frost date — see the calendar above for exact timing.
What planting zone is Lewis County, WA?
Lewis County, Washington is in USDA Hardiness Zone 8a. The average last spring frost is April 25 and first fall frost is October 24.
Your Lewis County Garden Planner — Free
A 24-page printable planner built for Lewis County (Zone 8a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.