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When to Plant Hubbard Squash in Imperial County, CA

Imperial County, California Zone 10a May

Your May gardening checklist

Here's what deserves your attention in Imperial County, California this month. Everything below is tailored to Zone 10a and timed around your local frost dates.

Avg. last frost January 29
Avg. first frost December 20
Soil temp (4") 78°F
Watering Critical
Pest pressure High
Daylight 13.7 hrs
  1. Harvest hubbard squash as they ripen

    This is the payoff month. Bring a basket, bring a friend, and get into the beds.

Before June arrives, get these ready
  • First harvests: hubbard squash

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Hubbard squash is a large, bumpy-skinned winter squash with dense, sweet, dry flesh ideal for baking and pies. The hard shell allows storage for 6 months or more.

Imperial County, California is in USDA Zone 10a. The average last spring frost is January 29 and the first fall frost is December 20, giving you a growing season of approximately 325 days.

At an elevation of 181 feet, Imperial County receives approximately 16.8 inches of rainfall annually with predominantly loam soil. Summer highs average 93°F, providing good warmth for Hubbard Squash during the growing season. With low rainfall, drip irrigation is essential for growing Hubbard Squash successfully. Mulch heavily to conserve soil moisture.

Imperial County, CA (Zone 10a) Year-round
325 days
Last Spring Frost January 29
325 growing days
First Fall Frost December 20

Imperial County Soil Profile

Soil Type

Loam

Soil pH

5.7-7.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (186 days to spare)
Start indoors: Dec 19 Transplant: Jan 23 🍅 Harvest: May 8 – Jun 12
Recommended (50%) ✓ Fits season (178 days to spare)
Start indoors: Jan 1 Transplant: Feb 5 🍅 Harvest: May 21 – Jun 25
Safe Start (90%) ✓ Fits season (169 days to spare)
Start indoors: Jan 17 Transplant: Feb 21 🍅 Harvest: Jun 6 – Jul 11

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 Imperial County

How your county's soil matches Hubbard Squash's growing requirements.

Soil pH

Your soil pH (5.7–7.3) overlaps with Hubbard Squash's range (6.0–7.0), though not a perfect match.

Soil Texture

The loam soil in Imperial County is excellent for Hubbard Squash — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.4%). Annual compost additions will help Hubbard Squash.

How to Plant Hubbard Squash

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

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.2″/week
You supply
0.9″/week
Watering frequency 2-3 times/week
Season total 2,728 gal / 100 sq ft
Drought risk

Water stress score is 10/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Hubbard Squash

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

Month Hubbard Squash Needs Rainfall You Supplement Action
Jan 4.3" 3" 1.3" 💧 Light watering
Feb 4.3" 3.3" 1" 💧 Light watering
Mar 4.3" 3.1" 1.2" 💧 Light watering
Apr 4.3" 1.4" 2.9" 🚿 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" 0.6" 3.7" 🚿 Regular watering
Nov 4.3" 1.5" 2.8" 🚿 Regular watering
Dec 4.3" 3.3" 1" 💧 Light watering

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

Hubbard Squash 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.

Hubbard Squash needs ~2,172 GDD — county provides 6,438 GDD Excellent fit

Hubbard Squash Planting Timeline — Imperial County, CA

Hubbard Squash Planting Calendar

Activity When Date Range
Start Indoors January 1 Jan 1 – Jan 15
Transplant Outdoors February 5 Feb 5 – Feb 19
Direct Sow January 29 Jan 29 – Feb 19
Harvest May 21 May 21 – Jun 25

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 2-3 times/week

📅 Days to Maturity

100–120 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 10a

📆 Growing Season

325 days in Imperial County

Growing Tips for Hubbard Squash in Imperial County

Direct sow Hubbard Squash outdoors after January 29 in Imperial County when soil has warmed and frost danger has passed.

Common pests for Hubbard Squash in this region include squash vine borer and cucumber beetles. Use row covers early in the season and inspect plants weekly.

Imperial County receives only 17" of rain annually. Hubbard Squash needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Start seeds indoors in short-season areas. Requires ample space and rich soil. Harvest when the skin is very hard and the color is deep. Cure in the sun before storing.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Hubbard Squash in Imperial County, CA?

Imperial County is in Zone 10a with an average last frost of January 29. Plan your Hubbard Squash planting based on this frost date — see the calendar above for exact timing.

What planting zone is Imperial County, CA?

Imperial County, California is in USDA Hardiness Zone 10a. The average last spring frost is January 29 and first fall frost is December 20.

🌱

Your Imperial County Garden Planner — Free

A 24-page printable planner built for Imperial 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 Imperial County, CA. 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.