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When to Plant Mint in Adair County, IA

Adair County, Iowa Zone 5b May

Your May gardening checklist

Welcome to May in Zone 5b. These are the moves that will have the biggest impact on your growing season.

Avg. last frost April 24
Avg. first frost October 9
Soil temp (4") 58°F
Watering Low
Pest pressure Low
Daylight 14.3 hrs
  1. Harden off and plant mint

    Plant tomatoes deep — bury the stem up to the first true leaves to grow extra roots. Everything else goes in at the same depth it grew in the tray.

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Mint is a vigorous perennial herb with refreshing, aromatic leaves used in teas, cocktails, and cooking. It spreads aggressively by underground runners.

Adair County, Iowa is in USDA Zone 5b. The average last spring frost is April 24 and the first fall frost is October 9, giving you a growing season of approximately 168 days.

At an elevation of 554 feet, Adair County receives approximately 38.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84°F, so choose short-season varieties of Mint to ensure they mature before fall.

Adair County, IA (Zone 5b) Moderate season
168 days
Last Spring Frost April 24
168 growing days
First Fall Frost October 9

Adair County Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-6.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (29 days to spare)
Transplant: Apr 24 🍅 Harvest: Jun 26 – Sep 4
Recommended (50%) ✓ Fits season (28 days to spare)
Transplant: May 1 🍅 Harvest: Jul 3 – Sep 11
Safe Start (90%) ✓ Fits season (33 days to spare)
Transplant: May 11 🍅 Harvest: Jul 13 – Sep 21

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 Adair County

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

Soil pH

Your soil pH (6.1–6.7) is within Mint's preferred range (6.0–7.0).

Soil Texture

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

Organic Matter

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

How to Plant Mint

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

Succession Planting Mint

3
successive plantings in your 168-day season

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

Plant Water Budget

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

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Mint

Mint needs approximately 0.7 inches of water per week (3" per month). Here's how your county's rainfall compares month by month.

Month Mint Needs Rainfall You Supplement Action
Jan 1.7" 0" ❄️ Dormant
Feb 1.8" 0" ❄️ Dormant
Mar 2.5" 0" ❄️ Dormant
Apr 3" 4.3" 0" ✅ Rainfall sufficient
May 3" 4.3" 0" ✅ Rainfall sufficient
Jun 3" 4.7" 0" ✅ Rainfall sufficient
Jul 3" 3.8" 0" ✅ Rainfall sufficient
Aug 3" 4.4" 0" ✅ Rainfall sufficient
Sep 3" 3.2" 0" ✅ Rainfall sufficient
Oct 3" 2.8" 0.2" 💧 Light watering
Nov 2.8" 0" ❄️ Dormant
Dec 2.2" 0" ❄️ Dormant

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

Mint 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.

Mint needs ~975 GDD — county provides 2,184 GDD Excellent fit

Mint Planting Timeline — Adair County, IA

Mint Planting Calendar

Activity When Date Range
Transplant Outdoors May 1 May 1 – May 15
Harvest July 3 Jul 3 – Sep 11

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

0.7"/week · Natural rainfall sufficient

📅 Days to Maturity

60–90 days

🧪 Soil pH

Needs 6–7 · Your soil: ideal

🗺️ USDA Zone

Zone 5b

📆 Growing Season

168 days in Adair County

Growing Tips for Mint in Adair County

Direct sow Mint outdoors after April 24 in Adair County when soil has warmed and frost danger has passed.

General growing tips

Always grow mint in containers or with underground barriers to control spreading. Harvest regularly to keep plants compact. Cut plants back in late summer for a fresh fall flush.

Companion Planting

Good Companions

Avoid Planting Near

  • Parsley

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Mint in Adair County, IA?

Adair County is in Zone 5b with an average last frost of April 24. Plan your Mint planting based on this frost date — see the calendar above for exact timing.

What planting zone is Adair County, IA?

Adair County, Iowa is in USDA Hardiness Zone 5b. The average last spring frost is April 24 and first fall frost is October 9.

🌱

Your Adair County Garden Planner — Free

A 24-page printable planner built for Adair 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 Adair 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.