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When to Plant Bitter Melon in San Juan County, WA

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.

San Juan County, Washington is in USDA Zone 8a. The average last spring frost is March 26 and the first fall frost is November 3, giving you a growing season of approximately 222 days.

At an elevation of 371 feet, San Juan County receives approximately 40.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 82ยฐF, so choose short-season varieties of Bitter Melon to ensure they mature before fall.

San Juan County, WA (Zone 8a) Long season
222 days
Last Spring Frost March 26
222 growing days
First Fall Frost November 3

San Juan County Soil Profile

Soil Type

Silt Loam

Soil pH

5.4-6.4

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (105 days to spare)
Start indoors: Jan 29 Transplant: Apr 2 🍅 Harvest: Jun 4 – Jul 16
Recommended (50%) ✓ Fits season (103 days to spare)
Start indoors: Feb 5 Transplant: Apr 9 🍅 Harvest: Jun 11 – Jul 23
Safe Start (90%) ✓ Fits season (101 days to spare)
Start indoors: Mar 7 Transplant: May 9 🍅 Harvest: Jul 11 – Aug 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.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.5″/week
Watering frequency 1-2 times/week
Season total 1,040 gal / 100 sq ft
Bitter Melon needs ~862 GDD — county provides 2,553 GDD Excellent fit

Bitter Melon Planting Timeline โ€” San Juan County, WA

Bitter Melon Planting Calendar

Activity When Date Range
Start Indoors February 5 Feb 5 โ€“ Feb 19
Transplant Outdoors April 9 Apr 9 โ€“ Apr 23
Direct Sow April 2 Apr 2 โ€“ Apr 23
Harvest June 11 Jun 11 โ€“ Jul 23

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

Month-by-Month Timeline

MonthActivities
January โ€”
February Start Indoors
March โ€”
April Transplant Outdoors Direct Sow
May โ€”
June Harvest
July Harvest
August โ€”
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 8a

Growing Season

222 days

Growing Tips for San Juan 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 San Juan County, WA?

San Juan County is in Zone 8a with an average last frost of March 26. Plan your Bitter Melon planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is San Juan County, WA?

San Juan County, Washington is in USDA Hardiness Zone 8a. The average last spring frost is March 26 and first fall frost is November 3.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help San Juan County gardeners in Zone 8a 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 San Juan County, WA. Local conditions may vary. Last updated: April 2026.