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When to plant Mint in St. Joseph County County,

St. Joseph County County's 171-day season only supports one Mint planting per year. Sow between May 5 and May 19 for the best chance at full maturity before October 16.

When to Plant Mint in St. Joseph County, MI

Mint
St. Joseph County, Michigan Zone 6a June

Your June game plan for St. Joseph County, Michigan

If you only do a handful of things in the garden this June, make it these. They're sequenced around your zone's frost timing.

Avg. last frost April 28
Avg. first frost October 16
Soil temp (4") 68°F
Watering Low
Pest pressure High
Daylight 15 hrs
Before July arrives, get these ready
  • First harvests: mint

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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.

St. Joseph County, Michigan is in USDA Zone 6a. The average last spring frost is April 28 and the first fall frost is October 16, giving you a growing season of approximately 171 days.

At an elevation of 564 feet, St. Joseph County receives approximately 39.5 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.

St. Joseph County, MI (Zone 6a) Moderate season
171 days
Last Spring Frost April 28
171 growing days
First Fall Frost October 16
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St. Joseph County Soil Profile

Soil Type

Silt Loam

Soil pH

5.8-6.7

Drainage

Well Drained

Mint Planting Risk Windows

Early Start (70% safe) ✓ Fits season (25 days to spare)
Transplant: May 3 🍅 Harvest: Jul 5 – Sep 13
Recommended (50%) ✓ Fits season (31 days to spare)
Transplant: May 5 🍅 Harvest: Jul 7 – Sep 15
Safe Start (90%) ✓ Fits season (25 days to spare)
Transplant: May 22 🍅 Harvest: Jul 24 – Oct 2

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 St. Joseph County

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

Soil pH

Your soil pH (5.8–6.7) overlaps with Mint's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (5.2%) — 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 171-day season

Sow every 6.9 weeks. Last sowing by Jul 18 to harvest before frost.

Mint Water Budget

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

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 1.5" 0" ❄️ Dormant
Feb 1.6" 0" ❄️ Dormant
Mar 2.9" 0" ❄️ Dormant
Apr 3" 3.7" 0" ✅ Rainfall sufficient
May 3" 5" 0" ✅ Rainfall sufficient
Jun 3" 4.5" 0" ✅ Rainfall sufficient
Jul 3" 4.4" 0" ✅ Rainfall sufficient
Aug 3" 4.1" 0" ✅ Rainfall sufficient
Sep 3" 3.5" 0" ✅ Rainfall sufficient
Oct 3" 3" 0" ✅ Rainfall sufficient
Nov 2.9" 0" ❄️ Dormant
Dec 2.3" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in St. Joseph 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 2,223 GDD Excellent fit

Mint Planting Timeline — St. Joseph County, MI

Mint Planting Calendar

Activity When Date Range
Transplant Outdoors May 5 May 5 – May 19
Harvest July 7 Jul 7 – Sep 15

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

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: acceptable

🗺️ USDA Zone

Zone 6a

📆 Growing Season

171 days in St. Joseph County

Growing Tips for Mint in St. Joseph County

Direct sow Mint outdoors after April 28 in St. Joseph 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 St. Joseph County, MI?

St. Joseph County is in Zone 6a with an average last frost of April 28. Plan your Mint planting based on this frost date — see the calendar above for exact timing.

What planting zone is St. Joseph County, MI?

St. Joseph County, Michigan is in USDA Hardiness Zone 6a. The average last spring frost is April 28 and first fall frost is October 16.

When should I plant Mint in St. Joseph County County, ?

In St. Joseph County County, , plant Mint after the last frost (around April 28) and before the first frost (around October 16). Best results when soil holds above 50°F.

What growing zone is St. Joseph County County, for Mint?

St. Joseph County County sits in USDA Zone 6a. Mint grows reliably in zones 3a through 10b, so it's a good fit here.

Can Mint grow in St. Joseph County County's climate?

Yes — Mint grows well in St. Joseph County County's temperate climate. St. Joseph County County averages a 171-day frost-free season, with last frost around April 28 and first frost around October 16.

🌱

Your St. Joseph County Garden Planner — Free

A 22-page printable planner built for St. Joseph County (Zone 6a). 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 St. Joseph County, MI. Local conditions may vary. Last updated: June 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.