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When to Plant Spinach in Shasta County, CA

Shasta County, California Zone 9a May

Your May planting checklist for Shasta County, California

Each item below is timed to Shasta County, California's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost June 6
Avg. first frost September 21
Soil temp (4") 70°F
Watering Critical
Pest pressure High
Daylight 14.3 hrs
  1. Outdoor sowing time: spinach

    Mark the row. Birds and stray feet both have opinions about unmarked beds.

Get ahead of June
  • Transplants going out: 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.

Shasta County, California is in USDA Zone 9a. The average last spring frost is June 6 and the first fall frost is September 21, giving you a growing season of approximately 107 days.

At an elevation of 81 feet, Shasta County receives approximately 40.5 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 85°F, providing good warmth for Spinach during the growing season. Sandy soil warms quickly in spring — great for early planting — but Spinach will need more frequent watering and organic matter to retain nutrients.

Shasta County, CA (Zone 9a) Short season
107 days
Last Spring Frost June 6
107 growing days
First Fall Frost September 21

Shasta County Soil Profile

Soil Type

Sandy Loam

Soil pH

5.7-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (15 days to spare)
Start indoors: Apr 25 Transplant: May 23 🍅 Harvest: Jun 27 – Aug 29
Recommended (50%) ✓ Fits season (9 days to spare)
Start indoors: May 9 Transplant: Jun 6 🍅 Harvest: Jul 11 – Sep 12
Safe Start (90%) ✓ Fits season (12 days to spare)
Start indoors: May 25 Transplant: Jun 22 🍅 Harvest: Jul 27 – Sep 28

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 Shasta County

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

Soil pH

Your soil pH (5.7–6.8) is more acidic than Spinach prefers (6.5–7.5). Add garden lime to raise pH.

Soil Texture

Sandy soil in Shasta County warms quickly in spring but drains fast. Spinach will need more frequent watering and regular compost additions to retain nutrients.

Organic Matter

Organic matter is moderate (2.6%). 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

3
successive plantings in your 107-day season

Sow every 4 weeks. Last sowing by Aug 02 to harvest before frost.

For a dedicated fall crop, sow by Jul 27.

Plant Water Budget

Plant needs
0.7″/week
Rainfall provides
1.6″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — 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 7.7" 0" ❄️ Dormant
Feb 8" 0" ❄️ Dormant
Mar 6.8" 0" ❄️ Dormant
Apr 3.2" 0" ❄️ Dormant
May 1" 0" ❄️ Dormant
Jun 3" 0.2" 2.8" 🚿 Regular watering
Jul 3" 0" 3" 🚿 Regular watering
Aug 3" 0" 3" 🚿 Regular watering
Sep 3" 0.4" 2.6" 🚿 Regular watering
Oct 1.6" 0" ❄️ Dormant
Nov 4.4" 0" ❄️ Dormant
Dec 7.1" 0" ❄️ Dormant

Water needs are for active growing months only (Jun–Sep in Shasta 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 ~584 GDD — county provides 1,471 GDD Excellent fit

Spinach Planting Timeline — Shasta County, CA

Spinach Planting Calendar

Activity When Date Range
Start Indoors May 9 May 9 – May 23
Transplant Outdoors June 6 Jun 6 – Jun 20
Direct Sow May 16 May 16 – Jun 6
Harvest July 11 Jul 11 – Sep 12
Fall Sowing July 27 Jul 27 – Aug 10

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

0.7"/week · Natural rainfall sufficient

📅 Days to Maturity

35–50 days

🧪 Soil pH

Needs 6.5–7.5 · Your soil: too_acidic

🗺️ USDA Zone

Zone 9a

📆 Growing Season

107 days in Shasta County

Growing Tips for Spinach in Shasta County

Direct sow Spinach outdoors after June 06 in Shasta County when soil has warmed and frost danger has passed.

Sandy soil in Shasta County dries quickly — mulch Spinach with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.

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 Shasta 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 Shasta County, CA?

Shasta County is in Zone 9a with an average last frost of June 6. Plan your Spinach planting based on this frost date — see the calendar above for exact timing.

What planting zone is Shasta County, CA?

Shasta County, California is in USDA Hardiness Zone 9a. The average last spring frost is June 6 and first fall frost is September 21.

🌱

Your Shasta County Garden Planner — Free

A 24-page printable planner built for Shasta 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 Shasta 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.