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When to Plant Bitter Melon in Snohomish County, WA

Snohomish County, Washington Zone 8b May

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

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

Avg. last frost March 25
Avg. first frost November 2
Soil temp (4") 70°F
Watering High
Pest pressure High
Daylight 15 hrs
  1. Start bitter melon indoors

    These need a head start before your last frost (March 25). Sow into cells now so you're ready to transplant in a few weeks.

Before June arrives, get these ready
  • First harvests: 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.

Snohomish County, Washington is in USDA Zone 8b. The average last spring frost is March 25 and the first fall frost is November 2, giving you a growing season of approximately 222 days.

At an elevation of 230 feet, Snohomish County receives approximately 50.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 90°F, providing good warmth for Bitter Melon during the growing season. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Bitter Melon root diseases.

Snohomish County, WA (Zone 8b) Long season
222 days
Last Spring Frost March 25
222 growing days
First Fall Frost November 2
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Snohomish County Soil Profile

Soil Type

Silt Loam

Soil pH

5.7-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (104 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 4 Transplant: Apr 8 🍅 Harvest: Jun 10 – Jul 22
Safe Start (90%) ✓ Fits season (102 days to spare)
Start indoors: Feb 28 Transplant: May 2 🍅 Harvest: Jul 4 – Aug 15

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 Snohomish County

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

Soil pH

Your soil pH (5.7–6.8) overlaps with Bitter Melon's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (5.4%) — Bitter Melon will thrive.

How to Plant Bitter Melon

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

Succession Planting Bitter Melon

4
successive plantings in your 222-day season

Sow every 6.9 weeks. Last sowing by Aug 04 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 84 gal / 100 sq ft

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 7.7" 0" ❄️ Dormant
Feb 5.6" 0" ❄️ Dormant
Mar 4.3" 5" 0" ✅ Rainfall sufficient
Apr 4.3" 3.6" 0.7" 💧 Light watering
May 4.3" 2.6" 1.7" 💧 Light watering
Jun 4.3" 1.6" 2.7" 🚿 Regular watering
Jul 4.3" 0.7" 3.6" 🚿 Regular watering
Aug 4.3" 1" 3.3" 🚿 Regular watering
Sep 4.3" 2" 2.3" 🚿 Regular watering
Oct 4.3" 4.2" 0.1" 💧 Light watering
Nov 4.3" 8" 0" ✅ Rainfall sufficient
Dec 8.5" 0" ❄️ Dormant

Water needs are for active growing months only (Mar–Nov in Snohomish 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 ~1,312 GDD — county provides 3,885 GDD Excellent fit

Bitter Melon Planting Timeline — Snohomish County, WA

Bitter Melon Planting Calendar

Activity When Date Range
Start Indoors February 4 Feb 4 – Feb 18
Transplant Outdoors April 8 Apr 8 – Apr 22
Direct Sow April 1 Apr 1 – Apr 22
Harvest June 10 Jun 10 – Jul 22

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

Month-by-Month Timeline

MonthActivities
January
February Start Indoors
March
April Transplant Outdoors Direct Sow
May
June Harvest
July Harvest
August
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: acceptable

🗺️ USDA Zone

Zone 8b

📆 Growing Season

222 days in Snohomish County

Growing Tips for Bitter Melon in Snohomish County

Direct sow Bitter Melon outdoors after March 25 in Snohomish 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 Snohomish County, WA?

Snohomish County is in Zone 8b with an average last frost of March 25. Plan your Bitter Melon planting based on this frost date — see the calendar above for exact timing.

What planting zone is Snohomish County, WA?

Snohomish County, Washington is in USDA Hardiness Zone 8b. The average last spring frost is March 25 and first fall frost is November 2.

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Your Snohomish County Garden Planner — Free

A 24-page printable planner built for Snohomish County (Zone 8b). 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 Snohomish County, WA. 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.