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When to Plant Bitter Melon in Haines Borough, AK

Haines Borough, Alaska Zone 5b May

What to do in May

We've pulled the most time-sensitive tasks for Haines Borough, Alaska this May and put them front and centre. Tackle them in order.

Avg. last frost May 7
Avg. first frost September 29
Soil temp (4") 58°F
Watering High
Pest pressure Low
Daylight 16.6 hrs
  1. Set out bitter melon seedlings

    Frost risk is low now in Haines Borough, Alaska. If you've been covering beds overnight, you can stop.

  2. Direct-sow bitter melon

    Rake a smooth bed, make a shallow furrow, drop seeds at the spacing on the packet, water gently, walk away.

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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.

Haines Borough, Alaska is in USDA Zone 5b. The average last spring frost is May 7 and the first fall frost is September 29, giving you a growing season of approximately 145 days.

At an elevation of 1,921 feet, Haines Borough receives approximately 57.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 68°F, so choose short-season varieties of Bitter Melon to ensure they mature before fall. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Bitter Melon root diseases.

Haines Borough, AK (Zone 5b) Short season
145 days
Last Spring Frost May 7
145 growing days
First Fall Frost September 29

Haines Borough Soil Profile

Soil Type

Silt Loam

Soil pH

4.9-6.4

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (27 days to spare)
Start indoors: Mar 3 Transplant: May 12 🍅 Harvest: Jul 14 – Aug 25
Recommended (50%) ✓ Fits season (26 days to spare)
Start indoors: Mar 12 Transplant: May 21 🍅 Harvest: Jul 23 – Sep 3
Safe Start (90%) ✓ Fits season (24 days to spare)
Start indoors: Apr 2 Transplant: Jun 11 🍅 Harvest: Aug 13 – Sep 24

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 Haines Borough

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

Soil pH

Your soil pH (4.9–6.4) is more acidic than Bitter Melon prefers (6.0–7.0). Add garden lime to raise pH.

Soil Texture

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

Drainage

Drainage is adequate for Bitter Melon.

Organic Matter

Organic matter is excellent (6.6%) — Bitter Melon will thrive.

How to Plant Bitter Melon

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

Succession Planting Bitter Melon

2
successive plantings in your 145-day season

Sow every 6.9 weeks. Last sowing by Jul 01 to harvest before frost.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.7″/week
Watering frequency Natural rainfall sufficient
Season total 0 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 2.8" 0" ❄️ Dormant
Feb 2.6" 0" ❄️ Dormant
Mar 2" 0" ❄️ Dormant
Apr 2" 0" ❄️ Dormant
May 4.3" 2.7" 1.6" 💧 Light watering
Jun 4.3" 4" 0.3" 💧 Light watering
Jul 4.3" 8.1" 0" ✅ Rainfall sufficient
Aug 4.3" 8.5" 0" ✅ Rainfall sufficient
Sep 4.3" 10.6" 0" ✅ Rainfall sufficient
Oct 6.5" 0" ❄️ Dormant
Nov 4.1" 0" ❄️ Dormant
Dec 3.4" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Haines Borough). 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 ~75 GDD — county provides 145 GDD Excellent fit

Bitter Melon Planting Timeline — Haines Borough, AK

Bitter Melon Planting Calendar

Activity When Date Range
Start Indoors March 12 Mar 12 – Mar 26
Transplant Outdoors May 21 May 21 – Jun 4
Direct Sow May 14 May 14 – Jun 4
Harvest July 23 Jul 23 – Sep 3

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 Transplant Outdoors Direct Sow
July Harvest
August Harvest
September Harvest
October
November
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

60–90 days

🧪 Soil pH

Needs 6–7 · Your soil: too_acidic

🗺️ USDA Zone

Zone 5b

📆 Growing Season

145 days in Haines Borough

Growing Tips for Bitter Melon in Haines Borough

Direct sow Bitter Melon outdoors after May 07 in Haines Borough 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 Haines Borough, AK?

Haines Borough is in Zone 5b with an average last frost of May 7. Plan your Bitter Melon planting based on this frost date — see the calendar above for exact timing.

What planting zone is Haines Borough, AK?

Haines Borough, Alaska is in USDA Hardiness Zone 5b. The average last spring frost is May 7 and first fall frost is September 29.

🌱

Your Haines Borough Garden Planner — Free

A 24-page printable planner built for Haines Borough (Zone 5b). 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 Haines Borough, AK. 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.