Blog

When to plant Mint in Granite County, MT

Granite County sits in cold Zone 5a. Plant Mint June 5–June 19 for the single annual harvest; the September 20 first frost closes the window.

When to Plant Mint in Granite County, MT

Mint

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

Granite County, Montana is in USDA Zone 5a. The average last spring frost is May 29 and the first fall frost is September 20, giving you a growing season of approximately 114 days.

At an elevation of 7,177 feet, Granite County receives approximately 18.9 inches of rainfall annually with predominantly loam soil. Summer highs average 81°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.

Granite County, MT (Zone 5a) Short season
114 days
Last Spring Frost May 29
114 growing days
First Fall Frost September 20

Granite County Soil Profile

Soil Type

Loam

Soil pH

6.0-7.0

Drainage

Well Drained

Mint Planting Timeline — Granite County, MT

Mint Planting Calendar

Activity When Date Range
Transplant Outdoors June 5 Jun 5 – Jun 19
Harvest August 7 Aug 7 – Oct 16

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

High — keep soil consistently moist

📅 Days to Maturity

60–90 days

🧪 Soil pH

Needs 6–7 · Your soil: N/A

🗺️ USDA Zone

Zone 5a

📆 Growing Season

114 days in Granite County

Growing Tips for Granite County

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 Granite County, MT?

Granite County is in Zone 5a with an average last frost of May 29. Plan your Mint planting based on this frost date — see the calendar above for exact timing.

What planting zone is Granite County, MT?

Granite County, Montana is in USDA Hardiness Zone 5a. The average last spring frost is May 29 and first fall frost is September 20.

When should I plant Mint in Granite County, MT?

In Granite County, MT, plant Mint after the last frost (around May 29) and before the first frost (around September 20). Best results when soil holds above 50°F.

What growing zone is Granite County, MT for Mint?

Granite County sits in USDA Zone 5a. Mint grows reliably in zones 3a through 10b, so it's a good fit here.

Can Mint grow in Granite County's climate?

Yes — Mint grows well in Granite County's temperate climate. Granite County averages a 114-day frost-free season, with last frost around May 29 and first frost around September 20.

🌱

Your Granite County Garden Planner — Free

A 22-page printable planner built for Granite County (Zone 5a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

Instant PDF download. No spam, unsubscribe any time.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Granite County, MT. 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.