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When to Plant Pac Choi in Marathon County, WI

Marathon County, Wisconsin Zone 4b May

Your May gardening checklist

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

Avg. last frost May 11
Avg. first frost October 2
Soil temp (4") 55°F
Watering Low
Pest pressure Low
Daylight 14.6 hrs
  1. Move pac choi 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. Sow pac choi where they'll grow

    Mark the row. Birds and stray feet both have opinions about unmarked beds.

To set up a strong June, finish these tasks
  • Starting indoors: pac choi
  • First harvests: 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.

Marathon County, Wisconsin is in USDA Zone 4b. The average last spring frost is May 11 and the first fall frost is October 2, giving you a growing season of approximately 144 days.

At an elevation of 723 feet, Marathon County receives approximately 39.9 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.

Marathon County, WI (Zone 4b) Short season
144 days
Last Spring Frost May 11
144 growing days
First Fall Frost October 2
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Marathon County Soil Profile

Soil Type

Silt Loam

Soil pH

6-7.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (78 days to spare)
Start indoors: Mar 22 Transplant: May 3 🍅 Harvest: Jun 14 – Jul 12
Recommended (50%) ✓ Fits season (74 days to spare)
Start indoors: Mar 30 Transplant: May 11 🍅 Harvest: Jun 22 – Jul 20
Safe Start (90%) ✓ Fits season (77 days to spare)
Start indoors: Apr 9 Transplant: May 21 🍅 Harvest: Jul 2 – Jul 30

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 Marathon County

How your county's soil matches Pac Choi's growing requirements.

Soil pH

Your soil pH (6.0–7.3) is within Pac Choi's preferred range (6.0–7.5).

Soil Texture

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

Organic Matter

Organic matter is excellent (4.1%) — 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

4
successive plantings in your 144-day season

Sow every 4.6 weeks. Last sowing by Aug 08 to harvest before frost.

For a dedicated fall crop, sow by Jul 10.

Plant Water Budget

Plant needs
1.5″/week
Rainfall provides
1.2″/week
You supply
0.3″/week
Watering frequency 1-2 times/week
Season total 431 gal / 100 sq ft

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 1.7" 0" ❄️ Dormant
Feb 2" 0" ❄️ Dormant
Mar 2.7" 0" ❄️ Dormant
Apr 4.3" 0" ❄️ Dormant
May 6.5" 5" 1.5" 💧 Light watering
Jun 6.5" 4.5" 2" 💧 Light watering
Jul 6.5" 4.8" 1.7" 💧 Light watering
Aug 6.5" 4.6" 1.9" 💧 Light watering
Sep 6.5" 3.1" 3.4" 🚿 Regular watering
Oct 6.5" 3" 3.5" 🚿 Regular watering
Nov 2.4" 0" ❄️ Dormant
Dec 1.9" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Marathon 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 1,764 GDD Excellent fit

Pac Choi Planting Timeline — Marathon County, WI

Pac Choi 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 22 Jun 22 – Jul 20
Fall Sowing July 10 Jul 10 – Jul 24

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

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1.5"/week · 1-2 times/week

📅 Days to Maturity

40–55 days

🧪 Soil pH

Needs 6–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 4b

📆 Growing Season

144 days in Marathon County

Growing Tips for Pac Choi in Marathon County

Direct sow Pac Choi outdoors after May 11 in Marathon County when soil has warmed and frost danger has passed.

Your generous 144.0-day season in Marathon County allows multiple plantings of Pac Choi. Sow every 20.0 days for continuous harvest.

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 Marathon County, WI?

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

What planting zone is Marathon County, WI?

Marathon County, Wisconsin is in USDA Hardiness Zone 4b. The average last spring frost is May 11 and first fall frost is October 2.

🌱

Your Marathon County Garden Planner — Free

A 24-page printable planner built for Marathon 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.

Instant PDF download. No spam, unsubscribe any time.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Marathon 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.