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When to Plant Snap Peas in Iron County, MI

Iron County, Michigan Zone 4a May

May in Iron County, Michigan — your action list

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

Avg. last frost May 26
Avg. first frost September 21
Soil temp (4") 53°F
Watering Low
Pest pressure Low
Daylight 14.8 hrs
A few tasks this May that'll pay off in June
  • Transplants going out: snap peas
  • Direct-sowing: snap peas

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Snap peas have edible pods with plump, sweet peas inside, combining the best features of snow peas and garden peas. They are a garden favorite for fresh eating.

Iron County, Michigan is in USDA Zone 4a. The average last spring frost is May 26 and the first fall frost is September 21, giving you a growing season of approximately 118 days.

At an elevation of 531 feet, Iron County receives approximately 42 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Snap Peas to ensure they mature before fall.

Iron County, MI (Zone 4a) Short season
118 days
Last Spring Frost May 26
118 growing days
First Fall Frost September 21
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Iron County Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-6.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 18 Transplant: Jun 10 🍅 Harvest: Aug 5 – Sep 30
Recommended (50%) ✗ May not fit
Start indoors: Mar 24 Transplant: Jun 16 🍅 Harvest: Aug 11 – Oct 6
Safe Start (90%) ✗ May not fit
Start indoors: Apr 9 Transplant: Jul 2 🍅 Harvest: Aug 27 – Oct 22

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 Iron County

How your county's soil matches Snap Peas's growing requirements.

Soil pH

Your soil pH (6.1–6.9) is within Snap Peas's preferred range (6.0–7.5).

Soil Texture

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

Organic Matter

Organic matter is excellent (4.5%) — Snap Peas will thrive.

How to Plant Snap Peas

1"
Planting Depth
4"
Between Plants
18"
Between Rows

Succession Planting Snap Peas

2
successive plantings in your 118-day season

Sow every 6.3 weeks. Last sowing by Jul 13 to harvest before frost.

Plant Water Budget

Plant needs
0.7″/week
Rainfall provides
1.5″/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 Snap Peas

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

Month Snap Peas Needs Rainfall You Supplement Action
Jan 1.9" 0" ❄️ Dormant
Feb 2.1" 0" ❄️ Dormant
Mar 3.2" 0" ❄️ Dormant
Apr 3.9" 0" ❄️ Dormant
May 3" 4.5" 0" ✅ Rainfall sufficient
Jun 3" 4.8" 0" ✅ Rainfall sufficient
Jul 3" 4.3" 0" ✅ Rainfall sufficient
Aug 3" 4.7" 0" ✅ Rainfall sufficient
Sep 3" 3.8" 0" ✅ Rainfall sufficient
Oct 3" 0" ❄️ Dormant
Nov 3.3" 0" ❄️ Dormant
Dec 2.5" 0" ❄️ Dormant

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

Snap Peas 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.

Snap Peas needs ~766 GDD — county provides 1,445 GDD Excellent fit

Snap Peas Planting Timeline — Iron County, MI

Snap Peas Planting Calendar

Activity When Date Range
Start Indoors March 24 Mar 24 – Apr 7
Transplant Outdoors June 16 Jun 16 – Jun 30
Direct Sow June 9 Jun 9 – Jun 30
Harvest August 11 Aug 11 – Oct 6

Plant 1" deep · 4" apart · Rows 18" apart

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.7"/week · Natural rainfall sufficient

📅 Days to Maturity

55–70 days

🧪 Soil pH

Needs 6–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 4a

📆 Growing Season

118 days in Iron County

Growing Tips for Snap Peas in Iron County

Direct sow Snap Peas outdoors after May 26 in Iron County when soil has warmed and frost danger has passed.

Common pests for Snap Peas in this region include bean beetles and aphids. Use row covers early in the season and inspect plants weekly.

General growing tips

Direct sow in early spring as soon as soil can be worked. Provide a trellis 4-6 feet tall. Harvest when pods are plump and snap cleanly when bent.

Companion Planting

Good Companions

Avoid Planting Near

  • Onion
  • Garlic

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Snap Peas in Iron County, MI?

Iron County is in Zone 4a with an average last frost of May 26. Plan your Snap Peas planting based on this frost date — see the calendar above for exact timing.

What planting zone is Iron County, MI?

Iron County, Michigan is in USDA Hardiness Zone 4a. The average last spring frost is May 26 and first fall frost is September 21.

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Your Iron County Garden Planner — Free

A 24-page printable planner built for Iron 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 Iron County, MI. 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.