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When to Plant Napa Cabbage in Mason County, MI

Mason County, Michigan Zone 6a April

Top priorities for Mason County, Michigan gardeners in April

April rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Mason County, Michigan.

Avg. last frost May 15
Avg. first frost October 7
Soil temp (4") 44°F
Watering Moderate
Pest pressure Low
Daylight 13.2 hrs
Get ahead of May
  • Transplants going out: napa cabbage
  • Direct-sowing: 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.

Mason County, Michigan is in USDA Zone 5b. The average last spring frost is May 15 and the first fall frost is October 7, giving you a growing season of approximately 145 days.

At an elevation of 1,318 feet, Mason County receives approximately 34.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Napa Cabbage during the growing season.

Mason County, MI (Zone 5b) Short season
145 days
Last Spring Frost May 15
145 growing days
First Fall Frost October 7

Mason 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 (55 days to spare)
Start indoors: Apr 3 Transplant: May 8 🍅 Harvest: Jul 3 – Aug 7
Recommended (50%) ✓ Fits season (54 days to spare)
Start indoors: Apr 10 Transplant: May 15 🍅 Harvest: Jul 10 – Aug 14
Safe Start (90%) ✓ Fits season (56 days to spare)
Start indoors: Apr 24 Transplant: May 29 🍅 Harvest: Jul 24 – Aug 28

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 Mason County

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

Soil pH

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

Soil Texture

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

Organic Matter

Organic matter is excellent (4.5%) — Napa Cabbage will thrive.

How to Plant Napa Cabbage

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

Fall planting: Sow 10 weeks before your first frost date for a fall harvest.

Succession Planting Napa Cabbage

3
successive plantings in your 145-day season

Sow every 6.3 weeks. Last sowing by Jul 24 to harvest before frost.

For a dedicated fall crop, sow by Jul 29.

Plant Water Budget

Plant needs
1.5″/week
Rainfall provides
1.0″/week
You supply
0.5″/week
Watering frequency 1-2 times/week
Season total 650 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 1.3" 0" ❄️ Dormant
Feb 1.7" 0" ❄️ Dormant
Mar 2.5" 0" ❄️ Dormant
Apr 3.1" 0" ❄️ Dormant
May 6.5" 3.3" 3.2" 💧 Light watering
Jun 6.5" 4.5" 2" 💧 Light watering
Jul 6.5" 4.1" 2.4" 💧 Light watering
Aug 6.5" 3.9" 2.6" 💧 Light watering
Sep 6.5" 3.3" 3.2" 💧 Light watering
Oct 6.5" 2.9" 3.6" 🚿 Regular watering
Nov 2.1" 0" ❄️ Dormant
Dec 1.7" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Mason 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 ~894 GDD — county provides 1,993 GDD Excellent fit

Napa Cabbage Planting Timeline — Mason County, MI

Napa Cabbage Planting Calendar

Activity When Date Range
Start Indoors April 10 Apr 10 – Apr 24
Transplant Outdoors May 15 May 15 – May 29
Direct Sow May 1 May 1 – May 22
Harvest July 10 Jul 10 – Aug 14
Fall Sowing July 29 Jul 29 – Aug 12

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 Fall Sowing Harvest
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 5b

📆 Growing Season

145 days in Mason County

Growing Tips for Napa Cabbage in Mason County

Direct sow Napa Cabbage outdoors after May 15 in Mason 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 Mason County, MI?

Mason County is in Zone 5b with an average last frost of May 15. Plan your Napa Cabbage planting based on this frost date — see the calendar above for exact timing.

What planting zone is Mason County, MI?

Mason County, Michigan is in USDA Hardiness Zone 5b. The average last spring frost is May 15 and first fall frost is October 7.

🌱

Your Mason County Garden Planner — Free

A 24-page printable planner built for Mason County (Zone 5b). 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 Mason County, MI. 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.