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When to Plant Garlic Chives in Mahaska County, IA

Mahaska County, Iowa Zone 5b May

Your May gardening checklist

A quick May briefing for Mahaska County, Iowa gardeners — what's urgent, what's next, and what can wait.

Avg. last frost April 27
Avg. first frost October 9
Soil temp (4") 58°F
Watering Moderate
Pest pressure Low
Daylight 14.3 hrs
  1. Transplant garlic chives outside

    Pinch off the lowest leaves on each seedling before you plant — it reduces water loss while the roots catch up.

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Garlic chives are a perennial herb with flat leaves that have a mild garlic flavor. They produce attractive white flower clusters and are used in Asian cooking.

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 Garlic Chives 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 (26 days to spare)
Transplant: Apr 28 🍅 Harvest: Jun 30 – Sep 8
Recommended (50%) ✓ Fits season (25 days to spare)
Transplant: May 4 🍅 Harvest: Jul 6 – Sep 14
Safe Start (90%) ✓ Fits season (21 days to spare)
Transplant: May 21 🍅 Harvest: Jul 23 – Oct 1

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 Garlic Chives's growing requirements.

Soil pH

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

Soil Texture

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

Organic Matter

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

How to Plant Garlic Chives

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

Succession Planting Garlic Chives

3
successive plantings in your 165-day season

Sow every 6.9 weeks. Last sowing by Jul 11 to harvest before frost.

Plant Water Budget

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

Monthly Watering Guide for Garlic Chives

Garlic Chives needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.

Month Garlic Chives Needs Rainfall You Supplement Action
Jan 1.1" 0" ❄️ Dormant
Feb 1.3" 0" ❄️ Dormant
Mar 2.5" 0" ❄️ Dormant
Apr 2.2" 3.1" 0" ✅ Rainfall sufficient
May 2.2" 3.4" 0" ✅ Rainfall sufficient
Jun 2.2" 4.5" 0" ✅ Rainfall sufficient
Jul 2.2" 3.3" 0" ✅ Rainfall sufficient
Aug 2.2" 3.2" 0" ✅ Rainfall sufficient
Sep 2.2" 3.2" 0" ✅ Rainfall sufficient
Oct 2.2" 2.4" 0" ✅ Rainfall sufficient
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.

Garlic Chives 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.

Garlic Chives needs ~919 GDD — county provides 2,021 GDD Excellent fit

Garlic Chives Planting Timeline — Mahaska County, IA

Garlic Chives Planting Calendar

Activity When Date Range
Transplant Outdoors May 4 May 4 – May 18
Harvest July 6 Jul 6 – Sep 14

Plant 0.5" deep · 8" apart · Rows 12" apart

Month-by-Month Timeline

MonthActivities
January
February
March
April
May Transplant Outdoors
June
July Harvest
August Harvest
September Harvest
October
November
December
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Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.5"/week · Natural rainfall sufficient

📅 Days to Maturity

60–90 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 5b

📆 Growing Season

165 days in Mahaska County

Growing Tips for Garlic Chives in Mahaska County

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

Common pests for Garlic Chives in this region include onion maggots and thrips. Use row covers early in the season and inspect plants weekly.

General growing tips

Start from seed or divisions. Cut flower stalks before seeds set to prevent aggressive self-seeding. Both leaves and flower buds are edible and flavorful.

Companion Planting

Good Companions

Avoid Planting Near

  • Peas
  • Green Beans

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Garlic Chives in Mahaska County, IA?

Mahaska County is in Zone 5b with an average last frost of April 27. Plan your Garlic Chives 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.

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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.