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When to Plant Spinach in McPherson County, SD

McPherson County, South Dakota Zone 4b May

Your May game plan for McPherson County, South Dakota

If you only do a handful of things in the garden this May, make it these. They're sequenced around your zone's frost timing.

Avg. last frost May 11
Avg. first frost September 27
Soil temp (4") 49°F
Watering Moderate
Pest pressure Low
Daylight 14.7 hrs
  1. Get spinach in the ground

    Pinch off the lowest leaves on each seedling before you plant — it reduces water loss while the roots catch up.

  2. Plant spinach from seed, right in the garden

    Rake a smooth bed, make a shallow furrow, drop seeds at the spacing on the packet, water gently, walk away.

A few tasks this May that'll pay off in June
  • 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.

McPherson County, South Dakota is in USDA Zone 4b. The average last spring frost is May 11 and the first fall frost is September 27, giving you a growing season of approximately 139 days.

At an elevation of 637 feet, McPherson County receives approximately 21.4 inches of rainfall annually with predominantly loam soil. Summer highs average 79°F, so choose short-season varieties of Spinach to ensure they mature before fall.

McPherson County, SD (Zone 4b) Short season
139 days
Last Spring Frost May 11
139 growing days
First Fall Frost September 27
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McPherson County Soil Profile

Soil Type

Loam

Soil pH

6.7-7.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (45 days to spare)
Start indoors: Mar 21 Transplant: May 2 🍅 Harvest: Jun 6 – Aug 8
Recommended (50%) ✓ Fits season (41 days to spare)
Start indoors: Mar 30 Transplant: May 11 🍅 Harvest: Jun 15 – Aug 17
Safe Start (90%) ✓ Fits season (42 days to spare)
Start indoors: Apr 9 Transplant: May 21 🍅 Harvest: Jun 25 – Aug 27

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 McPherson County

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

Soil pH

Your soil pH (6.7–7.9) overlaps with Spinach's range (6.5–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.0%) — 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 139-day season

Sow every 4 weeks. Last sowing by Aug 08 to harvest before frost.

For a dedicated fall crop, sow by Jul 05.

Plant Water Budget

Plant needs
0.7″/week
Rainfall provides
0.7″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 79 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 0.6" 0" ❄️ Dormant
Feb 0.8" 0" ❄️ Dormant
Mar 1.5" 0" ❄️ Dormant
Apr 2.2" 0" ❄️ Dormant
May 3" 2.8" 0.2" 💧 Light watering
Jun 3" 3.3" 0" ✅ Rainfall sufficient
Jul 3" 2.8" 0.2" 💧 Light watering
Aug 3" 2.7" 0.3" 💧 Light watering
Sep 3" 1.9" 1.1" 💧 Light watering
Oct 1.5" 0" ❄️ Dormant
Nov 0.8" 0" ❄️ Dormant
Dec 0.5" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in McPherson 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 ~393 GDD — county provides 1,285 GDD Excellent fit

Spinach Planting Timeline — McPherson County, SD

Spinach Planting Calendar

Activity When Date Range
Start Indoors March 30 Mar 30 – Apr 13
Transplant Outdoors May 11 May 11 – May 25
Direct Sow May 4 May 4 – May 25
Harvest June 15 Jun 15 – Aug 17
Fall Sowing July 5 Jul 5 – Jul 19

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

Month-by-Month Timeline

MonthActivities
January
February
March Start Indoors
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 · Only during dry spells

📅 Days to Maturity

35–50 days

🧪 Soil pH

Needs 6.5–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 4b

📆 Growing Season

139 days in McPherson County

Growing Tips for Spinach in McPherson County

Direct sow Spinach outdoors after May 11 in McPherson County when soil has warmed and frost danger has passed.

Your generous 139.0-day season in McPherson 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 McPherson County, SD?

McPherson County is in Zone 4b with an average last frost of May 11. Plan your Spinach planting based on this frost date — see the calendar above for exact timing.

What planting zone is McPherson County, SD?

McPherson County, South Dakota is in USDA Hardiness Zone 4b. The average last spring frost is May 11 and first fall frost is September 27.

🌱

Your McPherson County Garden Planner — Free

A 24-page printable planner built for McPherson County (Zone 4b). 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 McPherson County, SD. 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.