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When to Plant Savoy Cabbage in Mahaska County, IA

Mahaska County, Iowa Zone 5b May

Your May planting checklist for Mahaska County, Iowa

Your garden in Mahaska County, Iowa is working on a schedule, even when you're not. Here's where you should be this May.

Avg. last frost April 27
Avg. first frost October 9
Soil temp (4") 58°F
Watering Moderate
Pest pressure Low
Daylight 14.3 hrs
Coming up in June — start thinking about
  • Starting indoors: savoy cabbage

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Savoy cabbage has crinkled, deeply veined leaves that form looser heads than regular cabbage. It has a milder, sweeter flavor and is more cold-tolerant.

Mahaska County, Iowa is in USDA Zone 5b. The average last spring frost is April 27 and the first fall frost is October 9, giving you a growing season of approximately 165 days.

At an elevation of 511 feet, Mahaska County receives approximately 32.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Savoy Cabbage to ensure they mature before fall.

Mahaska County, IA (Zone 5b) Moderate season
165 days
Last Spring Frost April 27
165 growing days
First Fall Frost October 9
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Mahaska County Soil Profile

Soil Type

Silt Loam

Soil pH

5.7-7.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (40 days to spare)
Start indoors: Mar 17 Transplant: Apr 21 🍅 Harvest: Jun 30 – Aug 25
Recommended (50%) ✓ Fits season (39 days to spare)
Start indoors: Mar 23 Transplant: Apr 27 🍅 Harvest: Jul 6 – Aug 31
Safe Start (90%) ✓ Fits season (35 days to spare)
Start indoors: Apr 9 Transplant: May 14 🍅 Harvest: Jul 23 – Sep 17

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 Mahaska County

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

Soil pH

Your soil pH (5.7–7.3) overlaps with Savoy Cabbage's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.1%) — Savoy Cabbage will thrive.

How to Plant Savoy 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 Savoy Cabbage

2
successive plantings in your 165-day season

Sow every 8 weeks. Last sowing by Jun 21 to harvest before frost.

For a dedicated fall crop, sow by Jul 31.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 265 gal / 100 sq ft

Monthly Watering Guide for Savoy Cabbage

Savoy Cabbage needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Savoy Cabbage Needs Rainfall You Supplement Action
Jan 1.1" 0" ❄️ Dormant
Feb 1.3" 0" ❄️ Dormant
Mar 2.5" 0" ❄️ Dormant
Apr 4.3" 3.1" 1.2" 💧 Light watering
May 4.3" 3.4" 0.9" 💧 Light watering
Jun 4.3" 4.5" 0" ✅ Rainfall sufficient
Jul 4.3" 3.3" 1" 💧 Light watering
Aug 4.3" 3.2" 1.1" 💧 Light watering
Sep 4.3" 3.2" 1.1" 💧 Light watering
Oct 4.3" 2.4" 1.9" 💧 Light watering
Nov 2.4" 0" ❄️ Dormant
Dec 1.9" 0" ❄️ Dormant

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

Savoy 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.

Savoy Cabbage needs ~1,102 GDD — county provides 2,021 GDD Excellent fit

Savoy Cabbage Planting Timeline — Mahaska County, IA

Savoy Cabbage Planting Calendar

Activity When Date Range
Start Indoors March 23 Mar 23 – Apr 6
Transplant Outdoors April 27 Apr 27 – May 11
Direct Sow April 13 Apr 13 – May 4
Harvest July 6 Jul 6 – Aug 31
Fall Sowing July 31 Jul 31 – Aug 14

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 Fall Sowing Harvest
September
October
November
December
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Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

70–110 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 5b

📆 Growing Season

165 days in Mahaska County

Growing Tips for Savoy Cabbage in Mahaska County

Direct sow Savoy Cabbage outdoors after April 27 in Mahaska County when soil has warmed and frost danger has passed.

Common pests for Savoy 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. Savoy cabbage is more forgiving of temperature fluctuations than smooth-leaved types. Excellent for stuffed cabbage rolls.

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 Savoy Cabbage in Mahaska County, IA?

Mahaska County is in Zone 5b with an average last frost of April 27. Plan your Savoy Cabbage planting based on this frost date — see the calendar above for exact timing.

What planting zone is Mahaska County, IA?

Mahaska County, Iowa is in USDA Hardiness Zone 5b. The average last spring frost is April 27 and first fall frost is October 9.

🌱

Your Mahaska County Garden Planner — Free

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