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When to Plant Cabbage in Plymouth County, IA

Plymouth County, Iowa Zone 4b April

Your April game plan for Plymouth County, Iowa

April is a pivotal month for Plymouth County, Iowa gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost April 30
Avg. first frost October 6
Soil temp (4") 41°F
Watering Low
Pest pressure Low
Daylight 13.2 hrs
  1. Move cabbage into the garden

    Bring a watering can to the bed. Each transplant gets a drink the moment it's in the ground, not ten minutes later.

  2. Scatter cabbage into prepared beds

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

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Cabbage is a versatile cool-season crop that forms dense, leafy heads in green, red, or savoy varieties. It is a staple for coleslaw, sauerkraut, and many global cuisines.

Plymouth County, Iowa is in USDA Zone 4b. The average last spring frost is April 30 and the first fall frost is October 6, giving you a growing season of approximately 159 days.

At an elevation of 1,392 feet, Plymouth County receives approximately 38 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Cabbage to ensure they mature before fall.

Plymouth County, IA (Zone 4b) Moderate season
159 days
Last Spring Frost April 30
159 growing days
First Fall Frost October 6

Plymouth County Soil Profile

Soil Type

Silt Loam

Soil pH

6-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (45 days to spare)
Start indoors: Mar 10 Transplant: Apr 21 🍅 Harvest: Jun 23 – Aug 18
Recommended (50%) ✓ Fits season (40 days to spare)
Start indoors: Mar 19 Transplant: Apr 30 🍅 Harvest: Jul 2 – Aug 27
Safe Start (90%) ✓ Fits season (36 days to spare)
Start indoors: Apr 2 Transplant: May 14 🍅 Harvest: Jul 16 – Sep 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 Plymouth County

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

Soil pH

Your soil pH (6.0–7.2) is within Cabbage's preferred range (6.0–7.5).

Soil Texture

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

Organic Matter

Organic matter is excellent (4.7%) — Cabbage will thrive.

How to Plant 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 Cabbage

3
successive plantings in your 159-day season

Sow every 6.9 weeks. Last sowing by Jun 28 to harvest before frost.

For a dedicated fall crop, sow by Jul 14.

Plant Water Budget

Plant needs
0.9″/week
Rainfall provides
1.0″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft

Monthly Watering Guide for Cabbage

Cabbage needs approximately 0.9 inches of water per week (3.9" per month). Here's how your county's rainfall compares month by month.

Month Cabbage Needs Rainfall You Supplement Action
Jan 1.6" 0" ❄️ Dormant
Feb 1.4" 0" ❄️ Dormant
Mar 2.6" 0" ❄️ Dormant
Apr 3.9" 3.9" 0" ✅ Rainfall sufficient
May 3.9" 4.8" 0" ✅ Rainfall sufficient
Jun 3.9" 4.2" 0" ✅ Rainfall sufficient
Jul 3.9" 4.4" 0" ✅ Rainfall sufficient
Aug 3.9" 4.3" 0" ✅ Rainfall sufficient
Sep 3.9" 3.4" 0.5" 💧 Light watering
Oct 3.9" 2.7" 1.2" 💧 Light watering
Nov 2.8" 0" ❄️ Dormant
Dec 1.9" 0" ❄️ Dormant

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

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.

Cabbage needs ~980 GDD — county provides 1,947 GDD Excellent fit

Cabbage Planting Timeline — Plymouth County, IA

Cabbage Planting Calendar

Activity When Date Range
Start Indoors March 19 Mar 19 – Apr 2
Transplant Outdoors April 30 Apr 30 – May 14
Direct Sow April 23 Apr 23 – May 14
Harvest July 2 Jul 2 – Aug 27
Fall Sowing July 14 Jul 14 – Jul 28

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

Month-by-Month Timeline

MonthActivities
January
February
March Start Indoors
April Start Indoors Transplant Outdoors Direct Sow
May Transplant Outdoors Direct Sow
June
July Fall Sowing Harvest
August Harvest
September
October
November
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.9"/week · Natural rainfall sufficient

📅 Days to Maturity

60–100 days

🧪 Soil pH

Needs 6–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 4b

📆 Growing Season

159 days in Plymouth County

Growing Tips for Cabbage in Plymouth County

Direct sow Cabbage outdoors after April 30 in Plymouth County when soil has warmed and frost danger has passed.

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

General growing tips

Start seeds indoors 4-6 weeks before last frost. Space plants 18-24 inches apart. Keep soil evenly moist to prevent heads from splitting.

Companion Planting

Good Companions

Avoid Planting Near

  • Strawberries
  • Tomatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Cabbage in Plymouth County, IA?

Plymouth County is in Zone 4b with an average last frost of April 30. Plan your Cabbage planting based on this frost date — see the calendar above for exact timing.

What planting zone is Plymouth County, IA?

Plymouth County, Iowa is in USDA Hardiness Zone 4b. The average last spring frost is April 30 and first fall frost is October 6.

🌱

Your Plymouth County Garden Planner — Free

A 24-page printable planner built for Plymouth 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 Plymouth County, IA. 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.