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When to plant Bitter Melon in Pacifica, CA

Bitter Melon planted in Pacifica between January 18 and February 8 matures in 60–90 days — well before the December 12 first frost.

When to Plant Bitter Melon in Pacifica, CA

San Mateo County, California Zone 10a July

July to-do list for San Mateo County, California

A quick July briefing for San Mateo County, California gardeners — what's urgent, what's next, and what can wait.

Avg. last frost January 18
Avg. first frost December 12
Soil temp (4") 92°F
Watering Critical
Pest pressure High
Daylight 14.3 hrs
  1. Plan the fall garden

    Make a planting map for August. Tomatoes, peppers, brassicas, lettuce, root crops all go in over the next 8 weeks. Soil amendments and irrigation prep happen now.

  2. Keep heat-survivor crops productive

    Daily harvest of okra and southern peas keeps plants producing. Let pods over-mature and the plant stops setting new fruit.

  3. Watch for hurricane prep season

    August-October is hurricane season. Stake young trees, secure rain barrels, and plan how to protect tender transplants from high winds.

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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.

Pacifica, California is in USDA Zone 10a. The average last spring frost is January 18 and the first fall frost is December 12, giving you a growing season of approximately 328 days.

At an elevation of 277 feet, San Mateo County receives approximately 16.9 inches of rainfall annually with predominantly loam soil. Summer highs average 81°F, so choose short-season varieties of Bitter Melon to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Bitter Melon successfully. Mulch heavily to conserve soil moisture.

Pacifica, CA (Zone 10a) Year-round
328 days
Last Spring Frost January 18
328 growing days
First Fall Frost December 12

Pacifica Soil Profile

Soil Type

Loam

Soil pH

6.8-7.2

Drainage

Well Drained

Bitter Melon Planting Risk Windows

Early Start (70% safe) ✓ Fits season (213 days to spare)
Start indoors: Dec 3 Transplant: Jan 21 🍅 Harvest: Mar 25 – May 6
Recommended (50%) ✓ Fits season (216 days to spare)
Start indoors: Dec 7 Transplant: Jan 25 🍅 Harvest: Mar 29 – May 10
Safe Start (90%) ✓ Fits season (163 days to spare)
Start indoors: Feb 10 Transplant: Mar 31 🍅 Harvest: Jun 2 – Jul 14

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 Pacifica

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

Soil pH

Your soil pH (6.8–7.2) overlaps with Bitter Melon's range (6.0–7.0), though not a perfect match.

Soil Texture

The loam soil in San Mateo County 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 moderate (2.6%). Annual compost additions will help Bitter Melon.

How to Plant Bitter Melon

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

Succession Planting Bitter Melon

6
successive plantings in your 328-day season

Sow every 6.9 weeks. Last sowing by Sep 13 to harvest before frost.

Bitter Melon Water Budget

Plant needs
1.0″/week
Rainfall provides
0.2″/week
You supply
1.3″/week
Watering frequency 2-3 times/week
Season total 3,810 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — 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 4.3" 3.9" 0.4" 💧 Light watering
Feb 4.3" 3.4" 0.9" 💧 Light watering
Mar 4.3" 2.7" 1.6" 💧 Light watering
Apr 4.3" 1.2" 3.1" 🚿 Regular watering
May 4.3" 0.4" 3.9" 🚿 Regular watering
Jun 4.3" 0.1" 4.2" 🚿 Regular watering
Jul 4.3" 0" 4.3" 🚿 Regular watering
Aug 4.3" 0" 4.3" 🚿 Regular watering
Sep 4.3" 0.2" 4.1" 🚿 Regular watering
Oct 4.3" 0.7" 3.6" 🚿 Regular watering
Nov 4.3" 1.4" 2.9" 🚿 Regular watering
Dec 4.3" 2.9" 1.4" 💧 Light watering

Water needs are for active growing months only (Jan–Dec in San Mateo 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 ~806 GDD — county provides 3,536 GDD Excellent fit

Bitter Melon Planting Timeline — Pacifica, CA

Bitter Melon Planting Calendar

Activity When Date Range
Start Indoors December 7 Dec 7 – Dec 21
Transplant Outdoors January 25 Jan 25 – Feb 8
Direct Sow January 18 Jan 18 – Feb 8
Harvest March 29 Mar 29 – May 10

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 2-3 times/week

📅 Days to Maturity

60–90 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 10a

📆 Growing Season

328 days in San Mateo County

Growing Tips for Bitter Melon in Pacifica

Direct sow Bitter Melon outdoors after January 18 in San Mateo 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.

San Mateo County receives only 17" of rain annually. Bitter Melon needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

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 →

When should I plant Bitter Melon in Pacifica, CA?

In Pacifica, CA, plant Bitter Melon after the last frost (around January 18) and before the first frost (around December 12). Best results when soil holds above 50°F.

What growing zone is Pacifica, CA for Bitter Melon?

Pacifica sits in USDA Zone 10a. Bitter Melon grows reliably in zones 5a through 11b, so it's a good fit here.

Can Bitter Melon grow in Pacifica's climate?

Yes — Bitter Melon grows well in Pacifica's temperate climate. Pacifica averages a 329-day frost-free season, with last frost around January 18 and first frost around December 12.

🌱

Your San Mateo County Garden Planner — Free

A 22-page printable planner built for San Mateo County (Zone 10a). 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 San Mateo County, CA. Local conditions may vary. Last updated: July 2026.