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When to Plant Pac Choi in Iron County, MI

Iron County, Michigan Zone 4a May

Iron County, Michigan gardeners: here's your May plan

A quick May briefing for Iron County, Michigan gardeners — what's urgent, what's next, and what can wait.

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. Move pac choi from tray to bed

    Bring a watering can to the bed. Each transplant gets a drink the moment it's in the ground, not ten minutes later.

  2. Direct-sow pac choi

    Keep the top inch of soil moist until germination — a gentle morning watering for 5–7 days does the job.

Get ahead of June
  • Fall sowing: pac choi

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Pac choi (baby bok choy) is a compact variety of Chinese cabbage with tender leaves and crisp stems. It grows quickly and is ideal for containers and small spaces.

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 Pac Choi 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 (47 days to spare)
Start indoors: Apr 8 Transplant: May 20 🍅 Harvest: Jul 1 – Jul 29
Recommended (50%) ✓ Fits season (48 days to spare)
Start indoors: Apr 14 Transplant: May 26 🍅 Harvest: Jul 7 – Aug 4
Safe Start (90%) ✓ Fits season (50 days to spare)
Start indoors: Apr 30 Transplant: Jun 11 🍅 Harvest: Jul 23 – Aug 20

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 Pac Choi's growing requirements.

Soil pH

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

Soil Texture

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

Organic Matter

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

How to Plant Pac Choi

1"
Planting Depth
15"
Between Plants
24"
Between Rows

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

Succession Planting Pac Choi

3
successive plantings in your 118-day season

Sow every 4.6 weeks. Last sowing by Jul 28 to harvest before frost.

For a dedicated fall crop, sow by Jun 29.

Plant Water Budget

Plant needs
1.5″/week
Rainfall provides
1.5″/week
You supply
0.0″/week
Watering frequency Only during dry spells
Season total 6 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Pac Choi

Pac Choi needs approximately 1.5 inches of water per week (6.5" per month). Here's how your county's rainfall compares month by month.

Month Pac Choi 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 6.5" 4.5" 2" 💧 Light watering
Jun 6.5" 4.8" 1.7" 💧 Light watering
Jul 6.5" 4.3" 2.2" 💧 Light watering
Aug 6.5" 4.7" 1.8" 💧 Light watering
Sep 6.5" 3.8" 2.7" 💧 Light watering
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.

Pac Choi 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.

Pac Choi needs ~582 GDD — county provides 1,445 GDD Excellent fit

Pac Choi Planting Timeline — Iron County, MI

Pac Choi 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 7 Jul 7 – Aug 4
Fall Sowing June 29 Jun 29 – Jul 13

Plant 1" deep · 15" apart · Rows 24" 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
October
November
December

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1.5"/week · Only during dry spells

📅 Days to Maturity

40–55 days

🧪 Soil pH

Needs 6–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 4a

📆 Growing Season

118 days in Iron County

Growing Tips for Pac Choi in Iron County

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

Common pests for Pac Choi in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.

General growing tips

Direct sow in spring or fall. Grows best in cool weather. Space 6 inches apart for baby pac choi. Harvest whole plants or cut outer leaves as needed.

Companion Planting

Good Companions

Avoid Planting Near

  • Strawberries

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Pac Choi in Iron County, MI?

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