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When to Plant Bitter Melon in Walworth County, WI

Walworth County, Wisconsin Zone 5a April

April to-do list for Walworth County, Wisconsin

Each item below is timed to Walworth County, Wisconsin's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost April 26
Avg. first frost October 13
Soil temp (4") 44°F
Watering Low
Pest pressure Low
Daylight 13.2 hrs
May will be here before you know it — start on
  • Transplants going out: bitter melon
  • Direct-sowing: bitter melon

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Bitter melon is a tropical vine producing warty, bitter fruits used in Asian and Indian cuisine. The intense bitterness is prized for its culinary and health properties.

Walworth County, Wisconsin is in USDA Zone 5a. The average last spring frost is April 26 and the first fall frost is October 13, giving you a growing season of approximately 170 days.

At an elevation of 1,101 feet, Walworth County receives approximately 39.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87°F, providing good warmth for Bitter Melon during the growing season.

Walworth County, WI (Zone 5a) Moderate season
170 days
Last Spring Frost April 26
170 growing days
First Fall Frost October 13
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Walworth County Soil Profile

Soil Type

Silt Loam

Soil pH

6.2-6.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (50 days to spare)
Start indoors: Feb 25 Transplant: May 6 🍅 Harvest: Jul 8 – Aug 19
Recommended (50%) ✓ Fits season (51 days to spare)
Start indoors: Mar 1 Transplant: May 10 🍅 Harvest: Jul 12 – Aug 23
Safe Start (90%) ✓ Fits season (49 days to spare)
Start indoors: Mar 17 Transplant: May 26 🍅 Harvest: Jul 28 – Sep 8

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 Walworth County

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

Soil pH

Your soil pH (6.2–6.9) is within Bitter Melon's preferred range (6.0–7.0).

Soil Texture

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

Organic Matter

Organic matter is excellent (4.4%) — Bitter Melon will thrive.

How to Plant Bitter Melon

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

Succession Planting Bitter Melon

3
successive plantings in your 170-day season

Sow every 6.9 weeks. Last sowing by Jul 15 to harvest before frost.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.0″/week
You supply
0.0″/week
Watering frequency Only during dry spells
Season total 39 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Bitter Melon

Bitter 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 Bitter Melon Needs Rainfall You Supplement Action
Jan 1.9" 0" ❄️ Dormant
Feb 1.8" 0" ❄️ Dormant
Mar 2.5" 0" ❄️ Dormant
Apr 4.3" 3.8" 0.5" 💧 Light watering
May 4.3" 4.2" 0.1" 💧 Light watering
Jun 4.3" 4.7" 0" ✅ Rainfall sufficient
Jul 4.3" 4.9" 0" ✅ Rainfall sufficient
Aug 4.3" 4.1" 0.2" 💧 Light watering
Sep 4.3" 4.2" 0.1" 💧 Light watering
Oct 4.3" 2.9" 1.4" 💧 Light watering
Nov 2.7" 0" ❄️ Dormant
Dec 2" 0" ❄️ Dormant

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

Bitter 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.

Bitter Melon needs ~1,144 GDD — county provides 2,592 GDD Excellent fit

Bitter Melon Planting Timeline — Walworth County, WI

Bitter Melon Planting Calendar

Activity When Date Range
Start Indoors March 1 Mar 1 – Mar 15
Transplant Outdoors May 10 May 10 – May 24
Direct Sow May 3 May 3 – May 24
Harvest July 12 Jul 12 – Aug 23

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

Month-by-Month Timeline

MonthActivities
January
February
March Start Indoors
April
May Transplant Outdoors Direct Sow
June
July Harvest
August Harvest
September
October
November
December
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Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

60–90 days

🧪 Soil pH

Needs 6–7 · Your soil: ideal

🗺️ USDA Zone

Zone 5a

📆 Growing Season

170 days in Walworth County

Growing Tips for Bitter Melon in Walworth County

Direct sow Bitter Melon outdoors after April 26 in Walworth County when soil has warmed and frost danger has passed.

Common pests for Bitter 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 4 weeks before last frost. Provide a trellis for climbing. Harvest fruits while still green and firm. Reduce bitterness by salting sliced fruit before cooking.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Bitter Melon in Walworth County, WI?

Walworth County is in Zone 5a with an average last frost of April 26. Plan your Bitter Melon planting based on this frost date — see the calendar above for exact timing.

What planting zone is Walworth County, WI?

Walworth County, Wisconsin is in USDA Hardiness Zone 5a. The average last spring frost is April 26 and first fall frost is October 13.

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Your Walworth County Garden Planner — Free

A 24-page printable planner built for Walworth County (Zone 5a). 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 Walworth County, WI. Local conditions may vary. Last updated: April 2026.

Sources & credits

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