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When to Plant Watermelon in Outagamie County, WI

Outagamie County, Wisconsin Zone 5b May

Outagamie County, Wisconsin gardeners: here's your May plan

We've pulled the most time-sensitive tasks for Outagamie County, Wisconsin this May and put them front and centre. Tackle them in order.

Avg. last frost May 8
Avg. first frost October 5
Soil temp (4") 56°F
Watering Low
Pest pressure Low
Daylight 14.6 hrs
  1. Set out watermelon seedlings

    Plant tomatoes deep — bury the stem up to the first true leaves to grow extra roots. Everything else goes in at the same depth it grew in the tray.

  2. Seed watermelon outdoors

    Thin ruthlessly once seedlings are up. Crowded roots mean smaller crops from every plant.

To set up a strong June, finish these tasks
  • Starting indoors: watermelon

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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.

Outagamie County, Wisconsin is in USDA Zone 5b. The average last spring frost is May 8 and the first fall frost is October 5, giving you a growing season of approximately 150 days.

At an elevation of 1,052 feet, Outagamie County receives approximately 36.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Watermelon to ensure they mature before fall.

Outagamie County, WI (Zone 5b) Moderate season
150 days
Last Spring Frost May 8
150 growing days
First Fall Frost October 5

Outagamie County Soil Profile

Soil Type

Silt Loam

Soil pH

6.3-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (22 days to spare)
Start indoors: Mar 25 Transplant: May 13 🍅 Harvest: Jul 22 – Sep 9
Recommended (50%) ✓ Fits season (17 days to spare)
Start indoors: Apr 3 Transplant: May 22 🍅 Harvest: Jul 31 – Sep 18
Safe Start (90%) ✓ Fits season (19 days to spare)
Start indoors: Apr 16 Transplant: Jun 4 🍅 Harvest: Aug 13 – Oct 1

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 Outagamie County

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

Soil pH

Your soil pH (6.3–6.8) is within Watermelon's preferred range (6.0–7.5).

Soil Texture

The silt loam soil in Outagamie County is excellent for Watermelon — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is excellent (4.6%) — Watermelon will thrive.

How to Plant Watermelon

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

Succession Planting Watermelon

2
successive plantings in your 150-day season

Sow every 8 weeks. Last sowing by Jun 27 to harvest before frost.

Plant Water Budget

Plant needs
1.5″/week
Rainfall provides
1.0″/week
You supply
0.6″/week
Watering frequency 1-2 times/week
Season total 757 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

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 1.7" 0" ❄️ Dormant
Feb 1.6" 0" ❄️ Dormant
Mar 2.8" 0" ❄️ Dormant
Apr 3.5" 0" ❄️ Dormant
May 6.5" 4.8" 1.7" 💧 Light watering
Jun 6.5" 3.9" 2.6" 💧 Light watering
Jul 6.5" 4.1" 2.4" 💧 Light watering
Aug 6.5" 3.3" 3.2" 💧 Light watering
Sep 6.5" 3.5" 3" 💧 Light watering
Oct 6.5" 3" 3.5" 🚿 Regular watering
Nov 2.6" 0" ❄️ Dormant
Dec 1.8" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Outagamie 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 needs ~1,041 GDD — county provides 1,837 GDD Excellent fit

Watermelon Planting Timeline — Outagamie County, WI

Watermelon Planting Calendar

Activity When Date Range
Start Indoors April 3 Apr 3 – Apr 17
Transplant Outdoors May 22 May 22 – Jun 5
Direct Sow May 15 May 15 – Jun 5
Harvest July 31 Jul 31 – Sep 18

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

Month-by-Month Timeline

MonthActivities
January
February
March
April Start Indoors
May Transplant Outdoors Direct Sow
June Transplant Outdoors Direct Sow
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: ideal

🗺️ USDA Zone

Zone 5b

📆 Growing Season

150 days in Outagamie County

Growing Tips for Watermelon in Outagamie County

Direct sow Watermelon outdoors after May 08 in Outagamie 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.

Recommended Watermelon Varieties for Outagamie County

Compact, early melons for shorter seasons

Sugar Baby (75d) Blacktail Mountain (70d) Golden Midget (70d)

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Watermelon in Outagamie County, WI?

Outagamie County is in Zone 5b with an average last frost of May 8. Plan your Watermelon planting based on this frost date — see the calendar above for exact timing.

What planting zone is Outagamie County, WI?

Outagamie County, Wisconsin is in USDA Hardiness Zone 5b. The average last spring frost is May 8 and first fall frost is October 5.

🌱

Your Outagamie County Garden Planner — Free

A 24-page printable planner built for Outagamie County (Zone 5b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

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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 Outagamie County, WI. Local conditions may vary. Last updated: May 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.