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When to Plant Caraway in Mills County, IA

Mills County, Iowa Zone 5b May

This month in Mills County, Iowa

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

Avg. last frost April 26
Avg. first frost October 7
Soil temp (4") 58°F
Watering Low
Pest pressure Low
Daylight 14.3 hrs
  1. Start caraway under lights

    You're about 21 weeks out from your last frost — the perfect window to get these germinating indoors.

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Caraway is a biennial herb grown for its distinctive crescent-shaped seeds used in rye bread, sauerkraut, and European cuisine. The leaves and roots are also edible.

Mills County, Iowa is in USDA Zone 5b. The average last spring frost is April 26 and the first fall frost is October 7, giving you a growing season of approximately 164 days.

At an elevation of 1,355 feet, Mills County receives approximately 35.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Caraway during the growing season.

Mills County, IA (Zone 5b) Moderate season
164 days
Last Spring Frost April 26
164 growing days
First Fall Frost October 7
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Mills County Soil Profile

Soil Type

Silt Loam

Soil pH

6.3-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season
Start indoors: Mar 18 Transplant: Apr 15
Recommended (50%) ✓ Fits season
Start indoors: Mar 22 Transplant: Apr 19
Safe Start (90%) ✓ Fits season
Start indoors: Apr 7 Transplant: May 5

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 Mills County

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

Soil pH

Your soil pH (6.3–6.8) is within Caraway's preferred range (6.0–7.5).

Soil Texture

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

Drainage

Drainage is adequate for Caraway.

Organic Matter

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

How to Plant Caraway

0.5"
Planting Depth
8"
Between Plants
12"
Between Rows

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

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.9″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 574 gal / 100 sq ft

Monthly Watering Guide for Caraway

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

Month Caraway Needs Rainfall You Supplement Action
Jan 1.7" 0" ❄️ Dormant
Feb 1.4" 0" ❄️ Dormant
Mar 2.5" 0" ❄️ Dormant
Apr 4.3" 3" 1.3" 💧 Light watering
May 4.3" 4.4" 0" ✅ Rainfall sufficient
Jun 4.3" 4.3" 0" ✅ Rainfall sufficient
Jul 4.3" 4.2" 0.1" 💧 Light watering
Aug 4.3" 3.5" 0.8" 💧 Light watering
Sep 4.3" 3.3" 1" 💧 Light watering
Oct 4.3" 2.6" 1.7" 💧 Light watering
Nov 2.3" 0" ❄️ Dormant
Dec 2.1" 0" ❄️ Dormant

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

Caraway 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.

Caraway needs ~5,603 GDD — county provides 2,255 GDD May not mature

Caraway Planting Timeline — Mills County, IA

Caraway Planting Calendar

Activity When Date Range
Start Indoors March 22 Mar 22 – Apr 5
Transplant Outdoors April 19 Apr 19 – May 3
Direct Sow April 12 Apr 12 – May 3
Fall Sowing July 29 Jul 29 – Aug 12

Plant 0.5" deep · 8" apart · Rows 12" 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
August Fall Sowing
September
October
November
December
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Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

365–450 days

🧪 Soil pH

Needs 6–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 5b

📆 Growing Season

164 days in Mills County

Growing Tips for Caraway in Mills County

Direct sow Caraway outdoors after April 26 in Mills County when soil has warmed and frost danger has passed.

Your 164.0-day growing season in Mills County is tight for Caraway (365.0-450.0 days to maturity). Start indoors and choose early-maturing varieties.

Common pests for Caraway in this region include carrot rust fly and parsleyworm. Use row covers early in the season and inspect plants weekly.

General growing tips

Direct sow in spring or fall. Caraway produces seeds in its second year. Harvest seed heads when they turn brown. The young leaves can be used like parsley.

Companion Planting

Good Companions

Avoid Planting Near

  • Fennel

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Caraway in Mills County, IA?

Mills County is in Zone 5b with an average last frost of April 26. Plan your Caraway planting based on this frost date — see the calendar above for exact timing.

What planting zone is Mills County, IA?

Mills County, Iowa is in USDA Hardiness Zone 5b. The average last spring frost is April 26 and first fall frost is October 7.

🌱

Your Mills County Garden Planner — Free

A 24-page printable planner built for Mills 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 Mills County, IA. Local conditions may vary. Last updated: May 2026.

Sources & credits

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