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When to Plant Napa Cabbage in Clark County, WI

Clark County, Wisconsin Zone 4b May

May in the garden — Clark County, Wisconsin

We've pulled the most time-sensitive tasks for Clark County, Wisconsin this May and put them front and centre. Tackle them in order.

Avg. last frost May 13
Avg. first frost September 30
Soil temp (4") 54°F
Watering Low
Pest pressure Low
Daylight 14.6 hrs
  1. Move napa cabbage 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 napa cabbage

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

June will be here before you know it — start on
  • Starting indoors: napa cabbage

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Napa cabbage forms tall, barrel-shaped heads with tender, crinkled leaves and a mild, slightly sweet flavor. It is the primary cabbage used for kimchi.

Clark County, Wisconsin is in USDA Zone 4b. The average last spring frost is May 13 and the first fall frost is September 30, giving you a growing season of approximately 140 days.

At an elevation of 850 feet, Clark County receives approximately 39.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 82°F, so choose short-season varieties of Napa Cabbage to ensure they mature before fall.

Clark County, WI (Zone 4b) Short season
140 days
Last Spring Frost May 13
140 growing days
First Fall Frost September 30
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Clark County Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (54 days to spare)
Start indoors: Mar 24 Transplant: May 5 🍅 Harvest: Jun 30 – Aug 4
Recommended (50%) ✓ Fits season (49 days to spare)
Start indoors: Apr 1 Transplant: May 13 🍅 Harvest: Jul 8 – Aug 12
Safe Start (90%) ✓ Fits season (55 days to spare)
Start indoors: Apr 9 Transplant: May 21 🍅 Harvest: Jul 16 – 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 Clark County

How your county's soil matches Napa Cabbage's growing requirements.

Soil pH

Your soil pH (6.1–6.8) is within Napa Cabbage's preferred range (6.0–7.5).

Soil Texture

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

Organic Matter

Organic matter is moderate (3.9%). Annual compost additions will help Napa Cabbage.

How to Plant Napa Cabbage

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 Napa Cabbage

2
successive plantings in your 140-day season

Sow every 6.3 weeks. Last sowing by Jul 17 to harvest before frost.

For a dedicated fall crop, sow by Jul 08.

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 381 gal / 100 sq ft

Monthly Watering Guide for Napa Cabbage

Napa Cabbage 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 Napa Cabbage Needs Rainfall You Supplement Action
Jan 1.8" 0" ❄️ Dormant
Feb 2" 0" ❄️ Dormant
Mar 2.6" 0" ❄️ Dormant
Apr 3.9" 0" ❄️ Dormant
May 6.5" 4.6" 1.9" 💧 Light watering
Jun 6.5" 4.6" 1.9" 💧 Light watering
Jul 6.5" 4.2" 2.3" 💧 Light watering
Aug 6.5" 4.2" 2.3" 💧 Light watering
Sep 6.5" 3.7" 2.8" 💧 Light watering
Oct 2.8" 0" ❄️ Dormant
Nov 3" 0" ❄️ Dormant
Dec 2.4" 0" ❄️ Dormant

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

Napa Cabbage 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.

Napa Cabbage needs ~748 GDD — county provides 1,610 GDD Excellent fit

Napa Cabbage Planting Timeline — Clark County, WI

Napa Cabbage Planting Calendar

Activity When Date Range
Start Indoors April 1 Apr 1 – Apr 15
Transplant Outdoors May 13 May 13 – May 27
Direct Sow May 6 May 6 – May 27
Harvest July 8 Jul 8 – Aug 12
Fall Sowing July 8 Jul 8 – Jul 22

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
July Fall Sowing Harvest
August Harvest
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

55–75 days

🧪 Soil pH

Needs 6–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 4b

📆 Growing Season

140 days in Clark County

Growing Tips for Napa Cabbage in Clark County

Direct sow Napa Cabbage outdoors after May 13 in Clark County when soil has warmed and frost danger has passed.

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

General growing tips

Best grown as a fall crop. Direct sow in late summer, 60-70 days before first frost. Keep soil evenly moist. Bolt-resistant varieties are available for spring planting.

Companion Planting

Good Companions

Avoid Planting Near

  • Strawberries

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Napa Cabbage in Clark County, WI?

Clark County is in Zone 4b with an average last frost of May 13. Plan your Napa Cabbage planting based on this frost date — see the calendar above for exact timing.

What planting zone is Clark County, WI?

Clark County, Wisconsin is in USDA Hardiness Zone 4b. The average last spring frost is May 13 and first fall frost is September 30.

🌱

Your Clark County Garden Planner — Free

A 24-page printable planner built for Clark 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 Clark 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.