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When to Plant Bitter Melon in Mercer County, OH

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.

Mercer County, Ohio is in USDA Zone 5b. The average last spring frost is April 25 and the first fall frost is October 17, giving you a growing season of approximately 175 days.

At an elevation of 874 feet, Mercer County receives approximately 32.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84ยฐF, so choose short-season varieties of Bitter Melon to ensure they mature before fall.

Mercer County, OH (Zone 5b) Moderate season
175 days
Last Spring Frost April 25
175 growing days
First Fall Frost October 17

Mercer County Soil Profile

Soil Type

Silt Loam

Soil pH

5.9-6.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (53 days to spare)
Start indoors: Feb 25 Transplant: May 6 🍅 Harvest: Jul 8 – Aug 19
Recommended (50%) ✓ Fits season (56 days to spare)
Start indoors: Feb 28 Transplant: May 9 🍅 Harvest: Jul 11 – Aug 22
Safe Start (90%) ✓ Fits season (52 days to spare)
Start indoors: Mar 14 Transplant: May 23 🍅 Harvest: Jul 25 – Sep 5

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.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 335 gal / 100 sq ft
Bitter Melon needs ~975 GDD — county provides 2,275 GDD Excellent fit

Bitter Melon Planting Timeline โ€” Mercer County, OH

Bitter Melon Planting Calendar

Activity When Date Range
Start Indoors February 28 Feb 28 โ€“ Mar 14
Transplant Outdoors May 9 May 9 โ€“ May 23
Direct Sow May 2 May 2 โ€“ May 23
Harvest July 11 Jul 11 โ€“ Aug 22

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

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

60โ€“90 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 5b

Growing Season

175 days

Growing Tips for Mercer County

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

Level Up Your Garden

Frequently Asked Questions

When should I plant Bitter Melon in Mercer County, OH?

Mercer County is in Zone 5b with an average last frost of April 25. Plan your Bitter Melon planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Mercer County, OH?

Mercer County, Ohio is in USDA Hardiness Zone 5b. The average last spring frost is April 25 and first fall frost is October 17.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Mercer County gardeners in Zone 5b organize planting dates, track what's growing, and never miss a planting window.

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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 Mercer County, OH. Local conditions may vary. Last updated: April 2026.