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When to plant Spinach in Delta County, MI

Plant Spinach in Delta County after May 12; the prime window is April 28–May 19. A second sowing from August 5 to August 19 extends the harvest into fall.

When to Plant Spinach in Delta County, MI

Spinach
Delta County, Michigan Zone 5a July

What to do in July

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

Avg. last frost May 12
Avg. first frost October 14
Soil temp (4") 73°F
Watering Low
Pest pressure High
Daylight 15.2 hrs
  1. Collect spinach at their peak

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

Coming up in August — start thinking about
  • First harvests: spinach
  • Fall sowing: 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.

Delta County, Michigan is in USDA Zone 5a. The average last spring frost is May 12 and the first fall frost is October 14, giving you a growing season of approximately 155 days.

At an elevation of 921 feet, Delta County receives approximately 41.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Spinach to ensure they mature before fall.

Delta County, MI (Zone 5a) Moderate season
155 days
Last Spring Frost May 12
155 growing days
First Fall Frost October 14

Delta County Soil Profile

Soil Type

Silt Loam

Soil pH

6.2-6.8

Drainage

Well Drained

Spinach Planting Risk Windows

Early Start (70% safe) ✓ Fits season (57 days to spare)
Start indoors: Apr 1 Transplant: May 6 🍅 Harvest: Jun 10 – Aug 12
Recommended (50%) ✓ Fits season (57 days to spare)
Start indoors: Apr 7 Transplant: May 12 🍅 Harvest: Jun 16 – Aug 18
Safe Start (90%) ✓ Fits season (61 days to spare)
Start indoors: Apr 21 Transplant: May 26 🍅 Harvest: Jun 30 – Sep 1

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 Delta County

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

Soil pH

Your soil pH (6.2–6.8) overlaps with Spinach's range (6.5–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

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

How to Plant Spinach

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

Fall planting: Sow 10 weeks before your first frost date for a fall harvest.

Succession Planting Spinach

5
successive plantings in your 155-day season

Sow every 4 weeks. Last sowing by Aug 25 to harvest before frost.

For a dedicated fall crop, sow by Aug 05.

Spinach Water Budget

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

Water stress score is 6/10 — 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 1.8" 0" ❄️ Dormant
Feb 2" 0" ❄️ Dormant
Mar 2.8" 0" ❄️ Dormant
Apr 3.6" 0" ❄️ Dormant
May 3" 5.3" 0" ✅ Rainfall sufficient
Jun 3" 4.8" 0" ✅ Rainfall sufficient
Jul 3" 4.8" 0" ✅ Rainfall sufficient
Aug 3" 3.8" 0" ✅ Rainfall sufficient
Sep 3" 3.6" 0" ✅ Rainfall sufficient
Oct 3" 3.3" 0" ✅ Rainfall sufficient
Nov 3.2" 0" ❄️ Dormant
Dec 2" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Delta 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 ~521 GDD — county provides 1,898 GDD Excellent fit

Spinach Planting Timeline — Delta County, MI

Spinach Planting Calendar

Activity When Date Range
Start Indoors April 7 Apr 7 – Apr 21
Transplant Outdoors May 12 May 12 – May 26
Direct Sow April 28 Apr 28 – May 19
Harvest June 16 Jun 16 – Aug 18
Fall Sowing August 5 Aug 5 – Aug 19

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

Month-by-Month Timeline

MonthActivities
January
February
March
April Start Indoors Direct Sow
May Transplant Outdoors Direct Sow
June Harvest
July Harvest
August Fall Sowing Harvest
September
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: acceptable

🗺️ USDA Zone

Zone 5a

📆 Growing Season

155 days in Delta County

Growing Tips for Spinach in Delta County

Direct sow Spinach outdoors after May 12 in Delta County when soil has warmed and frost danger has passed.

Your generous 155.0-day season in Delta 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.

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 Delta County, MI?

Delta County is in Zone 5a with an average last frost of May 12. Plan your Spinach planting based on this frost date — see the calendar above for exact timing.

What planting zone is Delta County, MI?

Delta County, Michigan is in USDA Hardiness Zone 5a. The average last spring frost is May 12 and first fall frost is October 14.

When should I plant Spinach in Delta County, MI?

In Delta County, MI, plant Spinach after the last frost (around May 12) and before the first frost (around October 14). Best results when soil holds above 50°F.

What growing zone is Delta County, MI for Spinach?

Delta County sits in USDA Zone 5a. Spinach grows reliably in zones 2a through 10b, so it's a good fit here.

Can Spinach grow in Delta County's climate?

Yes — Spinach grows well in Delta County's temperate climate. Delta County averages a 155-day frost-free season, with last frost around May 12 and first frost around October 14.

🌱

Your Delta County Garden Planner — Free

A 22-page printable planner built for Delta County (Zone 5a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

Instant PDF download. No spam, unsubscribe any time.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Delta County, MI. Local conditions may vary. Last updated: July 2026.

Sources & credits

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