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When to Plant Pac Choi in Washburn County, WI

Washburn County, Wisconsin Zone 4a May

Your May planting checklist for Washburn County, Wisconsin

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 17
Avg. first frost September 25
Soil temp (4") 50°F
Watering Moderate
Pest pressure Low
Daylight 14.7 hrs
  1. Move pac choi into the garden

    Pick a cloudy afternoon or evening to plant. Less transplant shock, and your seedlings will barely blink.

  2. Sow pac choi where they'll grow

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

Get ahead of June
  • 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.

Washburn County, Wisconsin is in USDA Zone 4a. The average last spring frost is May 17 and the first fall frost is September 25, giving you a growing season of approximately 131 days.

At an elevation of 954 feet, Washburn County receives approximately 32.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 79°F, so choose short-season varieties of Pac Choi to ensure they mature before fall.

Washburn County, WI (Zone 4a) Short season
131 days
Last Spring Frost May 17
131 growing days
First Fall Frost September 25

Washburn 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 (53 days to spare)
Start indoors: Apr 2 Transplant: May 14 🍅 Harvest: Jun 25 – Jul 23
Recommended (50%) ✓ Fits season (61 days to spare)
Start indoors: Apr 5 Transplant: May 17 🍅 Harvest: Jun 28 – Jul 26
Safe Start (90%) ✓ Fits season (60 days to spare)
Start indoors: Apr 20 Transplant: Jun 1 🍅 Harvest: Jul 13 – Aug 10

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 Washburn 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 Washburn County is excellent for Pac Choi — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is excellent (4.3%) — 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 131-day season

Sow every 4.6 weeks. Last sowing by Aug 01 to harvest before frost.

For a dedicated fall crop, sow by Jul 03.

Plant Water Budget

Plant needs
1.5″/week
Rainfall provides
1.1″/week
You supply
0.5″/week
Watering frequency 1-2 times/week
Season total 632 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 1.4" 0" ❄️ Dormant
Feb 1.2" 0" ❄️ Dormant
Mar 2.2" 0" ❄️ Dormant
Apr 3.5" 0" ❄️ Dormant
May 6.5" 3.7" 2.8" 💧 Light watering
Jun 6.5" 3.6" 2.9" 💧 Light watering
Jul 6.5" 4" 2.5" 💧 Light watering
Aug 6.5" 3.6" 2.9" 💧 Light watering
Sep 6.5" 3.1" 3.4" 🚿 Regular watering
Oct 2.7" 0" ❄️ Dormant
Nov 2.1" 0" ❄️ Dormant
Dec 1.6" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Washburn 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 ~439 GDD — county provides 1,211 GDD Excellent fit

Pac Choi Planting Timeline — Washburn County, WI

Pac Choi Planting Calendar

Activity When Date Range
Start Indoors April 5 Apr 5 – Apr 19
Transplant Outdoors May 17 May 17 – May 31
Direct Sow May 10 May 10 – May 31
Harvest June 28 Jun 28 – Jul 26
Fall Sowing July 3 Jul 3 – Jul 17

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 Harvest
July Fall Sowing Harvest
August
September
October
November
December

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 4a

📆 Growing Season

131 days in Washburn County

Growing Tips for Pac Choi in Washburn County

Direct sow Pac Choi outdoors after May 17 in Washburn 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 Washburn County, WI?

Washburn County is in Zone 4a with an average last frost of May 17. Plan your Pac Choi planting based on this frost date — see the calendar above for exact timing.

What planting zone is Washburn County, WI?

Washburn County, Wisconsin is in USDA Hardiness Zone 4a. The average last spring frost is May 17 and first fall frost is September 25.

🌱

Your Washburn County Garden Planner — Free

A 24-page printable planner built for Washburn 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 Washburn 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.