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When to plant Mint in Glacier County, MT

Plant Mint in Glacier County during the brief May 29–June 12 window. With 119 frost-free days, fall plantings can't mature before September 18.

When to Plant Mint in Glacier County, MT

Mint
Glacier County, Montana Zone 4b July

Top priorities for Glacier County, Montana gardeners in July

Each item below is timed to Glacier County, Montana's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost May 22
Avg. first frost September 18
Soil temp (4") 48°F
Watering High
Pest pressure High
Daylight 15.6 hrs
  1. Bring in the mint

    Check every 1–2 days. Many of these get tough or go to seed if you wait too long.

Coming up in August — start thinking about
  • 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.

Glacier County, Montana is in USDA Zone 4b. The average last spring frost is May 22 and the first fall frost is September 18, giving you a growing season of approximately 119 days.

At an elevation of 8,147 feet, Glacier County receives approximately 13.3 inches of rainfall annually with predominantly loam soil. Summer highs average 80°F, so choose short-season varieties of Mint to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Mint successfully. Mulch heavily to conserve soil moisture.

Glacier County, MT (Zone 4b) Short season
119 days
Last Spring Frost May 22
119 growing days
First Fall Frost September 18

Glacier County Soil Profile

Soil Type

Loam

Soil pH

6.3-8.1

Drainage

Well Drained

Mint Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 22 🍅 Harvest: Jul 24 – Oct 2
Recommended (50%) ✗ May not fit
Transplant: May 29 🍅 Harvest: Jul 31 – Oct 9
Safe Start (90%) ✗ May not fit
Transplant: Jun 18 🍅 Harvest: Aug 20 – Oct 29

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 Glacier County

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

Soil pH

Your soil pH (6.3–8.1) is more alkaline than Mint prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.4%). Annual compost additions will help Mint.

How to Plant Mint

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

Succession Planting Mint

2
successive plantings in your 119-day season

Sow every 6.9 weeks. Last sowing by Jun 20 to harvest before frost.

Mint Water Budget

Plant needs
0.7″/week
Rainfall provides
0.5″/week
You supply
0.3″/week
Watering frequency Only during dry spells
Season total 293 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — 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 0.8" 0" ❄️ Dormant
Feb 0.8" 0" ❄️ Dormant
Mar 1" 0" ❄️ Dormant
Apr 1.3" 0" ❄️ Dormant
May 3" 1.6" 1.4" 💧 Light watering
Jun 3" 1" 2" 🚿 Regular watering
Jul 3" 1.3" 1.7" 🚿 Regular watering
Aug 3" 1.4" 1.6" 🚿 Regular watering
Sep 3" 1.1" 1.9" 🚿 Regular watering
Oct 1.3" 0" ❄️ Dormant
Nov 1" 0" ❄️ Dormant
Dec 0.7" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Glacier 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 ~750 GDD — county provides 1,190 GDD Excellent fit

Mint Planting Timeline — Glacier County, MT

Mint Planting Calendar

Activity When Date Range
Transplant Outdoors May 29 May 29 – Jun 12
Harvest July 31 Jul 31 – Oct 9

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

0.7"/week · Only during dry spells

📅 Days to Maturity

60–90 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 4b

📆 Growing Season

119 days in Glacier County

Growing Tips for Mint in Glacier County

Direct sow Mint outdoors after May 22 in Glacier 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 Glacier County, MT?

Glacier County is in Zone 4b with an average last frost of May 22. Plan your Mint planting based on this frost date — see the calendar above for exact timing.

What planting zone is Glacier County, MT?

Glacier County, Montana is in USDA Hardiness Zone 4b. The average last spring frost is May 22 and first fall frost is September 18.

When should I plant Mint in Glacier County, MT?

In Glacier County, MT, plant Mint after the last frost (around May 22) and before the first frost (around September 18). Best results when soil holds above 50°F.

What growing zone is Glacier County, MT for Mint?

Glacier County sits in USDA Zone 4b. Mint grows reliably in zones 3a through 10b, so it's a good fit here.

Can Mint grow in Glacier County's climate?

Yes — Mint grows well in Glacier County's temperate climate. Glacier County averages a 119-day frost-free season, with last frost around May 22 and first frost around September 18.

🌱

Your Glacier County Garden Planner — Free

A 22-page printable planner built for Glacier County (Zone 4b). 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 Glacier County, MT. Local conditions may vary. Last updated: July 2026.

Sources & credits

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