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When to Plant Spinach in Sawyer County, WI

Sawyer County, Wisconsin Zone 4a May

May in the garden — Sawyer County, Wisconsin

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

Avg. last frost May 17
Avg. first frost September 25
Soil temp (4") 50°F
Watering Low
Pest pressure Low
Daylight 14.7 hrs
  1. Move spinach into the garden

    Harden off for 7 days — a little more sun each day — before planting. That's the difference between a seedling that thrives and one that stalls.

  2. Seed spinach outdoors

    Your soil is 50°F — warm enough for these to germinate without babying.

Coming up in June — start thinking about
  • Starting indoors: spinach
  • 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.

Sawyer County, Wisconsin is in USDA Zone 4a. The average last spring frost is May 17 and the first fall frost is September 25, giving you a growing season of approximately 131 days.

At an elevation of 815 feet, Sawyer County receives approximately 36.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 78°F, so choose short-season varieties of Spinach to ensure they mature before fall.

Sawyer County, WI (Zone 4a) Short season
131 days
Last Spring Frost May 17
131 growing days
First Fall Frost September 25
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Sawyer County Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-7.1

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (25 days to spare)
Start indoors: Apr 2 Transplant: May 14 🍅 Harvest: Jun 18 – Aug 20
Recommended (50%) ✓ Fits season (33 days to spare)
Start indoors: Apr 5 Transplant: May 17 🍅 Harvest: Jun 21 – Aug 23
Safe Start (90%) ✓ Fits season (32 days to spare)
Start indoors: Apr 20 Transplant: Jun 1 🍅 Harvest: Jul 6 – Sep 7

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 Sawyer County

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

Soil pH

Your soil pH (6.1–7.1) overlaps with Spinach's range (6.5–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (5.0%) — Spinach will thrive.

How to Plant Spinach

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

Fall planting: Sow 12 weeks before your first frost date for a fall harvest.

Succession Planting Spinach

4
successive plantings in your 131-day season

Sow every 4 weeks. Last sowing by Aug 06 to harvest before frost.

For a dedicated fall crop, sow by Jul 03.

Plant Water Budget

Plant needs
0.7″/week
Rainfall provides
1.2″/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 1.6" 0" ❄️ Dormant
Feb 1.8" 0" ❄️ Dormant
Mar 2.7" 0" ❄️ Dormant
Apr 3.6" 0" ❄️ Dormant
May 3" 4.1" 0" ✅ Rainfall sufficient
Jun 3" 3.9" 0" ✅ Rainfall sufficient
Jul 3" 4" 0" ✅ Rainfall sufficient
Aug 3" 4" 0" ✅ Rainfall sufficient
Sep 3" 3.5" 0" ✅ Rainfall sufficient
Oct 3.1" 0" ❄️ Dormant
Nov 2.8" 0" ❄️ Dormant
Dec 1.7" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Sawyer 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 ~361 GDD — county provides 1,113 GDD Excellent fit

Spinach Planting Timeline — Sawyer County, WI

Spinach Planting Calendar

Activity When Date Range
Start Indoors April 5 Apr 5 – Apr 19
Transplant Outdoors May 17 May 17 – May 31
Direct Sow May 10 May 10 – May 31
Harvest June 21 Jun 21 – Aug 23
Fall Sowing July 3 Jul 3 – Jul 17

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

Month-by-Month Timeline

MonthActivities
January
February
March
April Start Indoors
May Transplant Outdoors Direct Sow
June Harvest
July Fall Sowing Harvest
August Harvest
September
October
November
December
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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 4a

📆 Growing Season

131 days in Sawyer County

Growing Tips for Spinach in Sawyer County

Direct sow Spinach outdoors after May 17 in Sawyer County when soil has warmed and frost danger has passed.

Your generous 131.0-day season in Sawyer 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 Sawyer County, WI?

Sawyer County is in Zone 4a with an average last frost of May 17. Plan your Spinach planting based on this frost date — see the calendar above for exact timing.

What planting zone is Sawyer County, WI?

Sawyer County, Wisconsin is in USDA Hardiness Zone 4a. The average last spring frost is May 17 and first fall frost is September 25.

🌱

Your Sawyer County Garden Planner — Free

A 24-page printable planner built for Sawyer County (Zone 4a). 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 Sawyer County, WI. 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.