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When to Plant Napa Cabbage in Pembina County, ND

Pembina County, North Dakota Zone 4a May

Your May game plan for Pembina County, North Dakota

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

Avg. last frost May 15
Avg. first frost September 28
Soil temp (4") 49°F
Watering Moderate
Pest pressure Low
Daylight 15 hrs
  1. Move napa cabbage from tray to bed

    Your last frost (May 15) has passed. These warm-season crops can handle outdoor soil now.

  2. Direct-sow napa cabbage

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

Get ahead of June
  • 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.

Pembina County, North Dakota is in USDA Zone 4a. The average last spring frost is May 15 and the first fall frost is September 28, giving you a growing season of approximately 136 days.

At an elevation of 958 feet, Pembina County receives approximately 26.5 inches of rainfall annually with predominantly loam soil. Summer highs average 79°F, so choose short-season varieties of Napa Cabbage to ensure they mature before fall.

Pembina County, ND (Zone 4a) Short season
136 days
Last Spring Frost May 15
136 growing days
First Fall Frost September 28

Pembina County Soil Profile

Soil Type

Loam

Soil pH

6.6-7.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (43 days to spare)
Start indoors: Mar 30 Transplant: May 11 🍅 Harvest: Jul 6 – Aug 10
Recommended (50%) ✓ Fits season (45 days to spare)
Start indoors: Apr 3 Transplant: May 15 🍅 Harvest: Jul 10 – Aug 14
Safe Start (90%) ✓ Fits season (44 days to spare)
Start indoors: Apr 18 Transplant: May 30 🍅 Harvest: Jul 25 – Aug 29

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 Pembina County

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

Soil pH

Your soil pH (6.6–7.3) is within Napa Cabbage's preferred range (6.0–7.5).

Soil Texture

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

Organic Matter

Organic matter is excellent (4.2%) — Napa Cabbage will thrive.

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 136-day season

Sow every 6.3 weeks. Last sowing by Jul 15 to harvest before frost.

For a dedicated fall crop, sow by Jul 06.

Plant Water Budget

Plant needs
1.5″/week
Rainfall provides
0.8″/week
You supply
0.7″/week
Watering frequency 1-2 times/week
Season total 825 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 0.7" 0" ❄️ Dormant
Feb 1" 0" ❄️ Dormant
Mar 1.7" 0" ❄️ Dormant
Apr 2.6" 0" ❄️ Dormant
May 6.5" 3.6" 2.9" 💧 Light watering
Jun 6.5" 4.7" 1.8" 💧 Light watering
Jul 6.5" 3.2" 3.3" 🚿 Regular watering
Aug 6.5" 3.4" 3.1" 💧 Light watering
Sep 6.5" 2.7" 3.8" 🚿 Regular watering
Oct 1.4" 0" ❄️ Dormant
Nov 0.8" 0" ❄️ Dormant
Dec 0.6" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Pembina 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 ~601 GDD — county provides 1,258 GDD Excellent fit

Napa Cabbage Planting Timeline — Pembina County, ND

Napa Cabbage Planting Calendar

Activity When Date Range
Start Indoors April 3 Apr 3 – Apr 17
Transplant Outdoors May 15 May 15 – May 29
Direct Sow May 8 May 8 – May 29
Harvest July 10 Jul 10 – Aug 14
Fall Sowing July 6 Jul 6 – Jul 20

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

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 4a

📆 Growing Season

136 days in Pembina County

Growing Tips for Napa Cabbage in Pembina County

Direct sow Napa Cabbage outdoors after May 15 in Pembina 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 Pembina County, ND?

Pembina County is in Zone 4a 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 Pembina County, ND?

Pembina County, North Dakota is in USDA Hardiness Zone 4a. The average last spring frost is May 15 and first fall frost is September 28.

🌱

Your Pembina County Garden Planner — Free

A 24-page printable planner built for Pembina 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 Pembina County, ND. 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.