Blog

When to Plant Melon in Washington County, WI

Washington County, Wisconsin Zone 5b May

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

If you only do a handful of things in the garden this May, make it these. They're sequenced around your zone's frost timing.

Avg. last frost April 27
Avg. first frost October 11
Soil temp (4") 56°F
Watering Moderate
Pest pressure Low
Daylight 14.5 hrs
  1. Move melon from tray to bed

    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. Scatter melon into prepared beds

    Keep the top inch of soil moist until germination — a gentle morning watering for 5–7 days does the job.

A few tasks this May that'll pay off in June
  • Starting indoors: melon

Instant PDF download. No spam, unsubscribe any time.

Melons are warm-season vine crops that produce sweet, juicy fruits in many varieties including muskmelon and honeydew. They need a long, hot growing season.

Washington County, Wisconsin is in USDA Zone 5b. The average last spring frost is April 27 and the first fall frost is October 11, giving you a growing season of approximately 167 days.

At an elevation of 1,141 feet, Washington County receives approximately 33.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Melon during the growing season.

Washington County, WI (Zone 5b) Moderate season
167 days
Last Spring Frost April 27
167 growing days
First Fall Frost October 11

Washington County Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-6.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (31 days to spare)
Start indoors: Mar 20 Transplant: May 8 🍅 Harvest: Jul 17 – Sep 4
Recommended (50%) ✓ Fits season (34 days to spare)
Start indoors: Mar 23 Transplant: May 11 🍅 Harvest: Jul 20 – Sep 7
Safe Start (90%) ✓ Fits season (32 days to spare)
Start indoors: Apr 8 Transplant: May 27 🍅 Harvest: Aug 5 – Sep 23

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 Washington County

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

Soil pH

Your soil pH (6.1–6.7) is within Melon's preferred range (6.0–7.0).

Soil Texture

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

Organic Matter

Organic matter is excellent (4.3%) — Melon will thrive.

How to Plant Melon

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

Succession Planting Melon

2
successive plantings in your 167-day season

Sow every 8 weeks. Last sowing by Jul 03 to harvest before frost.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.9″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 227 gal / 100 sq ft

Monthly Watering Guide for Melon

Melon needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Melon Needs Rainfall You Supplement Action
Jan 1.5" 0" ❄️ Dormant
Feb 1.4" 0" ❄️ Dormant
Mar 2.3" 0" ❄️ Dormant
Apr 4.3" 3.5" 0.8" 💧 Light watering
May 4.3" 3.5" 0.8" 💧 Light watering
Jun 4.3" 4.2" 0.1" 💧 Light watering
Jul 4.3" 3.3" 1" 💧 Light watering
Aug 4.3" 4" 0.3" 💧 Light watering
Sep 4.3" 2.8" 1.5" 💧 Light watering
Oct 4.3" 3" 1.3" 💧 Light watering
Nov 2.2" 0" ❄️ Dormant
Dec 2.1" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Washington County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Melon 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.

Melon needs ~1,169 GDD — county provides 2,296 GDD Excellent fit

Melon Planting Timeline — Washington County, WI

Melon Planting Calendar

Activity When Date Range
Start Indoors March 23 Mar 23 – Apr 6
Transplant Outdoors May 11 May 11 – May 25
Direct Sow May 4 May 4 – May 25
Harvest July 20 Jul 20 – Sep 7

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"/week · Only during dry spells

📅 Days to Maturity

70–100 days

🧪 Soil pH

Needs 6–7 · Your soil: ideal

🗺️ USDA Zone

Zone 5b

📆 Growing Season

167 days in Washington County

Growing Tips for Melon in Washington County

Direct sow Melon outdoors after April 27 in Washington County when soil has warmed and frost danger has passed.

Common pests for Melon 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 before transplanting. Plant on raised mounds of compost-enriched soil. Reduce watering as fruits ripen to concentrate sweetness.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes
  • Cucumber

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Melon in Washington County, WI?

Washington County is in Zone 5b with an average last frost of April 27. Plan your Melon planting based on this frost date — see the calendar above for exact timing.

What planting zone is Washington County, WI?

Washington County, Wisconsin is in USDA Hardiness Zone 5b. The average last spring frost is April 27 and first fall frost is October 11.

🌱

Your Washington County Garden Planner — Free

A 24-page printable planner built for Washington 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.

Instant PDF download. No spam, unsubscribe any time.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Washington 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.