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When to Plant Spinach in Ventura County, CA

Ventura County, California Zone 10a May

Top priorities for Ventura County, California gardeners in May

We've pulled the most time-sensitive tasks for Ventura County, California this May and put them front and centre. Tackle them in order.

Avg. last frost March 18
Avg. first frost November 15
Soil temp (4") 77°F
Watering Critical
Pest pressure High
Daylight 13.8 hrs
  1. Start harvesting spinach

    Taste as you pick. The first ripe produce is the best feedback loop you'll get all season.

June will be here before you know it — start on
  • First harvests: spinach

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Spinach is a nutrient-packed cool-season green that grows quickly in spring and fall. It is rich in iron, vitamins, and antioxidants and excellent raw or cooked.

Ventura County, California is in USDA Zone 10a. The average last spring frost is March 18 and the first fall frost is November 15, giving you a growing season of approximately 242 days.

At an elevation of 2,094 feet, Ventura County receives approximately 19.4 inches of rainfall annually with predominantly loam soil. Summer highs average 88°F, providing good warmth for Spinach during the growing season. With low rainfall, drip irrigation is essential for growing Spinach successfully. Mulch heavily to conserve soil moisture.

Ventura County, CA (Zone 10a) Long season
242 days
Last Spring Frost March 18
242 growing days
First Fall Frost November 15

Ventura County Soil Profile

Soil Type

Loam

Soil pH

6-7.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (153 days to spare)
Start indoors: Feb 1 Transplant: Mar 1 🍅 Harvest: Apr 5 – Jun 7
Recommended (50%) ✓ Fits season (144 days to spare)
Start indoors: Feb 18 Transplant: Mar 18 🍅 Harvest: Apr 22 – Jun 24
Safe Start (90%) ✓ Fits season (143 days to spare)
Start indoors: Mar 15 Transplant: Apr 12 🍅 Harvest: May 17 – Jul 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 Ventura County

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

Soil pH

Your soil pH (6.0–7.7) overlaps with Spinach's range (6.5–7.5), though not a perfect match.

Soil Texture

The loam soil in Ventura County is excellent for Spinach — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.3%). Annual compost additions will help Spinach.

How to Plant Spinach

0.5"
Planting Depth
6"
Between Plants
12"
Between Rows

Fall planting: Sow 8 weeks before your first frost date for a fall harvest.

Succession Planting Spinach

8
successive plantings in your 242-day season

Sow every 4 weeks. Last sowing by Sep 26 to harvest before frost.

For a dedicated fall crop, sow by Sep 20.

Plant Water Budget

Plant needs
0.7″/week
Rainfall provides
0.3″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 939 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Spinach

Spinach needs approximately 0.7 inches of water per week (3" per month). Here's how your county's rainfall compares month by month.

Month Spinach Needs Rainfall You Supplement Action
Jan 3.8" 0" ❄️ Dormant
Feb 4.4" 0" ❄️ Dormant
Mar 3" 3.2" 0" ✅ Rainfall sufficient
Apr 3" 1.5" 1.5" 🚿 Regular watering
May 3" 0.6" 2.4" 🚿 Regular watering
Jun 3" 0.1" 2.9" 🚿 Regular watering
Jul 3" 0" 3" 🚿 Regular watering
Aug 3" 0" 3" 🚿 Regular watering
Sep 3" 0.2" 2.8" 🚿 Regular watering
Oct 3" 0.8" 2.2" 🚿 Regular watering
Nov 3" 1.7" 1.3" 💧 Light watering
Dec 3.1" 0" ❄️ Dormant

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

Spinach 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.

Spinach needs ~680 GDD — county provides 3,872 GDD Excellent fit

Spinach Planting Timeline — Ventura County, CA

Spinach Planting Calendar

Activity When Date Range
Start Indoors February 18 Feb 18 – Mar 4
Transplant Outdoors March 18 Mar 18 – Apr 1
Direct Sow February 25 Feb 25 – Mar 18
Harvest April 22 Apr 22 – Jun 24
Fall Sowing September 20 Sep 20 – Oct 4

Plant 0.5" deep · 6" apart · Rows 12" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

0.7"/week · 1-2 times/week

📅 Days to Maturity

35–50 days

🧪 Soil pH

Needs 6.5–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 10a

📆 Growing Season

242 days in Ventura County

Growing Tips for Spinach in Ventura County

Direct sow Spinach outdoors after March 18 in Ventura County when soil has warmed and frost danger has passed.

Your generous 242.0-day season in Ventura County allows multiple plantings of Spinach. Sow every 17.0 days for continuous harvest.

General growing tips

Direct sow as soon as soil can be worked in spring. Plant in partial shade for summer crops to delay bolting. Succession plant every 2 weeks for continuous harvest.

Recommended Spinach Varieties for Ventura County

Slow-bolting spinach for warm springs — best as fall crop here

Bloomsdale Long Standing Tyee Space

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

🌾 Save Your Own Spinach Seeds
Life Cycle Annual
Pollination Wind Pollinated
How to Collect Let plants bolt. Harvest seed stalks when seeds turn tan.
Storage Store airtight; viable 5 years at 35°F, under 45% humidity.

Wind pollinated — isolate 1/2 mile for purity. Easy to let bolt in heat.

Frequently Asked Questions

When should I plant Spinach in Ventura County, CA?

Ventura County is in Zone 10a with an average last frost of March 18. Plan your Spinach planting based on this frost date — see the calendar above for exact timing.

What planting zone is Ventura County, CA?

Ventura County, California is in USDA Hardiness Zone 10a. The average last spring frost is March 18 and first fall frost is November 15.

🌱

Your Ventura County Garden Planner — Free

A 24-page printable planner built for Ventura 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 Ventura 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.