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When to Plant Watermelon in Racine County, WI

Racine County, Wisconsin Zone 5b May

Top priorities for Racine County, Wisconsin gardeners in May

May is a pivotal month for Racine County, Wisconsin gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost April 24
Avg. first frost October 13
Soil temp (4") 58°F
Watering Low
Pest pressure Low
Daylight 14.4 hrs
  1. Move watermelon into the garden

    Pick a cloudy afternoon or evening to plant. Less transplant shock, and your seedlings will barely blink.

  2. Scatter watermelon into prepared beds

    Mark the row. Birds and stray feet both have opinions about unmarked beds.

  3. Fire up the seed-starting tray: watermelon

    Give them 6–8 weeks indoors before the last frost and you'll transplant into warm soil with seedlings that are already leaping.

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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.

Racine County, Wisconsin is in USDA Zone 5b. The average last spring frost is April 24 and the first fall frost is October 13, giving you a growing season of approximately 172 days.

At an elevation of 513 feet, Racine County receives approximately 39 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84°F, so choose short-season varieties of Watermelon to ensure they mature before fall.

Racine County, WI (Zone 5b) Moderate season
172 days
Last Spring Frost April 24
172 growing days
First Fall Frost October 13

Racine County Soil Profile

Soil Type

Silt Loam

Soil pH

5.8-6.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (40 days to spare)
Start indoors: Mar 13 Transplant: May 1 🍅 Harvest: Jul 10 – Aug 28
Recommended (50%) ✓ Fits season (39 days to spare)
Start indoors: Mar 20 Transplant: May 8 🍅 Harvest: Jul 17 – Sep 4
Safe Start (90%) ✓ Fits season (40 days to spare)
Start indoors: Apr 7 Transplant: May 26 🍅 Harvest: Aug 4 – Sep 22

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 Racine County

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

Soil pH

Your soil pH (5.8–6.9) overlaps with Watermelon's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (5.0%) — Watermelon will thrive.

How to Plant Watermelon

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

Succession Planting Watermelon

2
successive plantings in your 172-day season

Sow every 8 weeks. Last sowing by Jul 05 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 838 gal / 100 sq ft

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 1.5" 0" ❄️ Dormant
Feb 1.9" 0" ❄️ Dormant
Mar 2.8" 0" ❄️ Dormant
Apr 6.5" 3.9" 2.6" 💧 Light watering
May 6.5" 4.3" 2.2" 💧 Light watering
Jun 6.5" 4.8" 1.7" 💧 Light watering
Jul 6.5" 4.7" 1.8" 💧 Light watering
Aug 6.5" 3.8" 2.7" 💧 Light watering
Sep 6.5" 3.5" 3" 💧 Light watering
Oct 6.5" 2.6" 3.9" 🚿 Regular watering
Nov 3" 0" ❄️ Dormant
Dec 2.3" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Racine 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 ~1,105 GDD — county provides 2,236 GDD Excellent fit

Watermelon Planting Timeline — Racine County, WI

Watermelon Planting Calendar

Activity When Date Range
Start Indoors March 20 Mar 20 – Apr 3
Transplant Outdoors May 8 May 8 – May 22
Direct Sow May 1 May 1 – May 22
Harvest July 17 Jul 17 – Sep 4

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

Month-by-Month Timeline

MonthActivities
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: acceptable

🗺️ USDA Zone

Zone 5b

📆 Growing Season

172 days in Racine County

Growing Tips for Watermelon in Racine County

Direct sow Watermelon outdoors after April 24 in Racine 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

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Watermelon in Racine County, WI?

Racine County is in Zone 5b with an average last frost of April 24. Plan your Watermelon planting based on this frost date — see the calendar above for exact timing.

What planting zone is Racine County, WI?

Racine County, Wisconsin is in USDA Hardiness Zone 5b. The average last spring frost is April 24 and first fall frost is October 13.

🌱

Your Racine County Garden Planner — Free

A 24-page printable planner built for Racine 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 Racine 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.