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When to Plant Napa Cabbage in Vernon County, WI

Vernon County, Wisconsin Zone 4b April

April in Vernon County, Wisconsin — your action list

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

Avg. last frost April 28
Avg. first frost October 9
Soil temp (4") 43°F
Watering Low
Pest pressure Low
Daylight 13.2 hrs
  1. Set out napa cabbage seedlings

    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. Scatter napa cabbage into prepared beds

    These tolerate cool soil, so you're not gambling by sowing now.

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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.

Vernon County, Wisconsin is in USDA Zone 4b. The average last spring frost is April 28 and the first fall frost is October 9, giving you a growing season of approximately 164 days.

At an elevation of 641 feet, Vernon County receives approximately 38.4 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.

Vernon County, WI (Zone 4b) Moderate season
164 days
Last Spring Frost April 28
164 growing days
First Fall Frost October 9

Vernon County Soil Profile

Soil Type

Silt Loam

Soil pH

6-7.1

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (71 days to spare)
Start indoors: Mar 13 Transplant: Apr 24 🍅 Harvest: Jun 19 – Jul 24
Recommended (50%) ✓ Fits season (73 days to spare)
Start indoors: Mar 17 Transplant: Apr 28 🍅 Harvest: Jun 23 – Jul 28
Safe Start (90%) ✓ Fits season (68 days to spare)
Start indoors: Apr 3 Transplant: May 15 🍅 Harvest: Jul 10 – Aug 14

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 Vernon County

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

Soil pH

Your soil pH (6.0–7.1) is within Napa Cabbage's preferred range (6.0–7.5).

Soil Texture

The silt loam soil in Vernon 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

3
successive plantings in your 164-day season

Sow every 6.3 weeks. Last sowing by Jul 26 to harvest before frost.

For a dedicated fall crop, sow by Jul 17.

Plant Water Budget

Plant needs
1.5″/week
Rainfall provides
1.0″/week
You supply
0.6″/week
Watering frequency 1-2 times/week
Season total 905 gal / 100 sq ft
Drought risk

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

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 1.5" 0" ❄️ Dormant
Feb 1.7" 0" ❄️ Dormant
Mar 2.8" 0" ❄️ Dormant
Apr 6.5" 4.1" 2.4" 💧 Light watering
May 6.5" 4.2" 2.3" 💧 Light watering
Jun 6.5" 4.6" 1.9" 💧 Light watering
Jul 6.5" 4.6" 1.9" 💧 Light watering
Aug 6.5" 4" 2.5" 💧 Light watering
Sep 6.5" 3.4" 3.1" 💧 Light watering
Oct 6.5" 3.1" 3.4" 🚿 Regular watering
Nov 2.6" 0" ❄️ Dormant
Dec 1.8" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Vernon 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 1,886 GDD Excellent fit

Napa Cabbage Planting Timeline — Vernon County, WI

Napa Cabbage Planting Calendar

Activity When Date Range
Start Indoors March 17 Mar 17 – Mar 31
Transplant Outdoors April 28 Apr 28 – May 12
Direct Sow April 21 Apr 21 – May 12
Harvest June 23 Jun 23 – Jul 28
Fall Sowing July 17 Jul 17 – Jul 31

Plant 1" deep · 15" apart · Rows 24" apart

Month-by-Month Timeline

MonthActivities
January
February
March Start Indoors
April Transplant Outdoors Direct Sow
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

55–75 days

🧪 Soil pH

Needs 6–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 4b

📆 Growing Season

164 days in Vernon County

Growing Tips for Napa Cabbage in Vernon County

Direct sow Napa Cabbage outdoors after April 28 in Vernon 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 Vernon County, WI?

Vernon County is in Zone 4b with an average last frost of April 28. Plan your Napa Cabbage planting based on this frost date — see the calendar above for exact timing.

What planting zone is Vernon County, WI?

Vernon County, Wisconsin is in USDA Hardiness Zone 4b. The average last spring frost is April 28 and first fall frost is October 9.

🌱

Your Vernon County Garden Planner — Free

A 24-page printable planner built for Vernon 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.

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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 Vernon County, WI. Local conditions may vary. Last updated: April 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.