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When to Plant Calabash in San Juan County, WA

San Juan County, Washington Zone 9a April

What to do in April

Your San Juan County, Washington garden is entering a new phase. Here's what's on the schedule for April and why each task matters now.

Avg. last frost March 26
Avg. first frost November 3
Soil temp (4") 58°F
Watering High
Pest pressure High
Daylight 13.4 hrs
  1. Plant out calabash

    Frost risk is low now in San Juan County, Washington. If you've been covering beds overnight, you can stop.

May prep starts now
  • Starting indoors: calabash

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Calabash (bottle gourd) is a tropical vine producing edible young fruits used in Asian and African cooking. Mature dried fruits serve as natural containers and utensils.

San Juan County, Washington is in USDA Zone 9a. 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 82°F, so choose short-season varieties of Calabash to ensure they mature before fall.

San Juan County, WA (Zone 9a) 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 (77 days to spare)
Start indoors: Feb 5 Transplant: Mar 26 🍅 Harvest: Jun 18 – Aug 13
Recommended (50%) ✓ Fits season (75 days to spare)
Start indoors: Feb 12 Transplant: Apr 2 🍅 Harvest: Jun 25 – Aug 20
Safe Start (90%) ✓ Fits season (73 days to spare)
Start indoors: Mar 14 Transplant: May 2 🍅 Harvest: Jul 25 – Sep 19

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 San Juan County

How your county's soil matches Calabash's growing requirements.

Soil pH

Your soil pH (5.4–6.4) is more acidic than Calabash prefers (6.0–7.5). Add garden lime to raise pH.

Soil Texture

The silt loam soil in San Juan County is excellent for Calabash — good drainage, moisture retention, and nutrient holding capacity.

Drainage

Drainage is adequate for Calabash.

Organic Matter

Organic matter is excellent (4.8%) — Calabash will thrive.

How to Plant Calabash

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

Succession Planting Calabash

3
successive plantings in your 222-day season

Sow every 9.1 weeks. Last sowing by Jul 06 to harvest before frost.

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

Monthly Watering Guide for Calabash

Calabash needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Calabash Needs Rainfall You Supplement Action
Jan 5.7" 0" ❄️ Dormant
Feb 4.7" 0" ❄️ Dormant
Mar 4.3" 4.1" 0.2" 💧 Light watering
Apr 4.3" 2.6" 1.7" 💧 Light watering
May 4.3" 2.6" 1.7" 💧 Light watering
Jun 4.3" 1.5" 2.8" 🚿 Regular watering
Jul 4.3" 0.6" 3.7" 🚿 Regular watering
Aug 4.3" 0.8" 3.5" 🚿 Regular watering
Sep 4.3" 1.8" 2.5" 🚿 Regular watering
Oct 4.3" 3.4" 0.9" 💧 Light watering
Nov 4.3" 6.4" 0" ✅ Rainfall sufficient
Dec 6.6" 0" ❄️ Dormant

Water needs are for active growing months only (Mar–Nov in San Juan County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Calabash 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.

Calabash needs ~1,150 GDD — county provides 2,553 GDD Excellent fit

Calabash Planting Timeline — San Juan County, WA

Calabash Planting Calendar

Activity When Date Range
Start Indoors February 12 Feb 12 – Feb 26
Transplant Outdoors April 2 Apr 2 – Apr 16
Direct Sow March 26 Mar 26 – Apr 16
Harvest June 25 Jun 25 – Aug 20

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

80–120 days

🧪 Soil pH

Needs 6–7.5 · Your soil: too_acidic

🗺️ USDA Zone

Zone 9a

📆 Growing Season

222 days in San Juan County

Growing Tips for Calabash in San Juan County

Direct sow Calabash outdoors after March 26 in San Juan County when soil has warmed and frost danger has passed.

Common pests for Calabash 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 early. Provide a very strong trellis for heavy fruits. Harvest young for cooking or let mature on the vine for crafts. Requires a long, warm season.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Calabash in San Juan County, WA?

San Juan County is in Zone 9a with an average last frost of March 26. Plan your Calabash planting based on this frost date — see the calendar above for exact timing.

What planting zone is San Juan County, WA?

San Juan County, Washington is in USDA Hardiness Zone 9a. The average last spring frost is March 26 and first fall frost is November 3.

🌱

Your San Juan County Garden Planner — Free

A 24-page printable planner built for San Juan County (Zone 9a). 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 Juan County, WA. Local conditions may vary. Last updated: April 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.