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When to Plant Celtuce in Iron County, MI

Iron County, Michigan Zone 4a May

What to do in May

Welcome to May in Zone 4a. These are the moves that will have the biggest impact on your growing season.

Avg. last frost May 26
Avg. first frost September 21
Soil temp (4") 53°F
Watering Low
Pest pressure Low
Daylight 14.8 hrs
  1. Transplant celtuce outside

    Plant tomatoes deep — bury the stem up to the first true leaves to grow extra roots. Everything else goes in at the same depth it grew in the tray.

  2. Plant celtuce from seed, right in the garden

    Thin ruthlessly once seedlings are up. Crowded roots mean smaller crops from every plant.

Before June arrives, get these ready
  • Fall sowing: celtuce

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Celtuce (stem lettuce) is a Chinese vegetable grown for its thick, crunchy stem rather than its leaves. The peeled stem has a mild, cucumber-like flavor.

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 Celtuce 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

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) ✓ Fits season (12 days to spare)
Start indoors: Apr 8 Transplant: May 20 🍅 Harvest: Jul 22 – Sep 2
Recommended (50%) ✓ Fits season (13 days to spare)
Start indoors: Apr 14 Transplant: May 26 🍅 Harvest: Jul 28 – Sep 8
Safe Start (90%) ✓ Fits season (15 days to spare)
Start indoors: Apr 30 Transplant: Jun 11 🍅 Harvest: Aug 13 – Sep 24

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 Celtuce's growing requirements.

Soil pH

Your soil pH (6.1–6.9) is within Celtuce's preferred range (6.0–7.0).

Soil Texture

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

Organic Matter

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

How to Plant Celtuce

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 Celtuce

2
successive plantings in your 118-day season

Sow every 6.9 weeks. Last sowing by Jun 23 to harvest before frost.

For a dedicated fall crop, sow by Jun 29.

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 Celtuce

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

Month Celtuce 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.

Celtuce 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.

Celtuce needs ~919 GDD — county provides 1,445 GDD Excellent fit

Celtuce Planting Timeline — Iron County, MI

Celtuce Planting Calendar

Activity When Date Range
Start Indoors April 14 Apr 14 – Apr 28
Transplant Outdoors May 26 May 26 – Jun 9
Direct Sow May 19 May 19 – Jun 9
Harvest July 28 Jul 28 – Sep 8
Fall Sowing June 29 Jun 29 – Jul 13

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 Transplant Outdoors Direct Sow Fall Sowing
July Fall Sowing Harvest
August Harvest
September Harvest
October
November
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.7"/week · Natural rainfall sufficient

📅 Days to Maturity

60–90 days

🧪 Soil pH

Needs 6–7 · Your soil: ideal

🗺️ USDA Zone

Zone 4a

📆 Growing Season

118 days in Iron County

Growing Tips for Celtuce in Iron County

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

Common pests for Celtuce in this region include aphids and slugs. Use row covers early in the season and inspect plants weekly.

General growing tips

Direct sow in spring or start indoors. Space 12 inches apart. Harvest when stems are about 1 inch in diameter. Peel the tough outer skin to reveal the tender center.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Celtuce in Iron County, MI?

Iron County is in Zone 4a with an average last frost of May 26. Plan your Celtuce 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.

🌱

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.